EP0202013A2 - Steering and control system for percussion boring tools - Google Patents
Steering and control system for percussion boring tools Download PDFInfo
- Publication number
- EP0202013A2 EP0202013A2 EP86302534A EP86302534A EP0202013A2 EP 0202013 A2 EP0202013 A2 EP 0202013A2 EP 86302534 A EP86302534 A EP 86302534A EP 86302534 A EP86302534 A EP 86302534A EP 0202013 A2 EP0202013 A2 EP 0202013A2
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- EP
- European Patent Office
- Prior art keywords
- housing
- tool
- boring
- tool according
- percussion tool
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Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B7/00—Special methods or apparatus for drilling
- E21B7/26—Drilling without earth removal, e.g. with self-propelled burrowing devices
- E21B7/267—Drilling devices with senders, e.g. radio-transmitters for position of drilling tool
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B4/00—Drives for drilling, used in the borehole
- E21B4/06—Down-hole impacting means, e.g. hammers
- E21B4/14—Fluid operated hammers
- E21B4/145—Fluid operated hammers of the self propelled-type, e.g. with a reverse mode to retract the device from the hole
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
- E21B47/02—Determining slope or direction
- E21B47/022—Determining slope or direction of the borehole, e.g. using geomagnetism
- E21B47/0228—Determining slope or direction of the borehole, e.g. using geomagnetism using electromagnetic energy or detectors therefor
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
- E21B47/12—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
- E21B47/13—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling by electromagnetic energy, e.g. radio frequency
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B7/00—Special methods or apparatus for drilling
- E21B7/04—Directional drilling
- E21B7/06—Deflecting the direction of boreholes
- E21B7/068—Deflecting the direction of boreholes drilled by a down-hole drilling motor
Definitions
- This invention relates generally to percussion boring tools, and to the steering and control of percussion boring tools.
- Utility Companies often find it necessary to install or replace piping beneath different types of surfaces such as streets, driveways, railroad tracks, etc. To reduce costs and public inconvenience by eliminating unnecessary excavation and restoration, utilities sometimes use underground boring tools to install the new or replacement pipes.
- Existing boring tools are suitable for boring short distances (up to 60 ft.), but are not sufficiently advanced to provide directional control for longer distances. This lack of control, coupled with the inability of these tools to detect and steer around obstacles, has limited their use to about 20% of all excavations, with the majority of the remaining excavations being performed by open-cut trenching methods.
- Conventional pneumatic and hydraulic percussion moles are designed to pierce and compact compressible soils for the installation of underground utilities without the necessity of digging large launching and retrieval pits, open cutting of pavement or reclamation of large areas of land.
- An internal striker or hammer reciprocates under the action of compressed air or hydraulic fluid to deliver high energy blows to the inner face of the body. These blows propel the tool through the soil to form an earthen casing within the soil that remains open to allow laying of cable or conduit. From early 1970 to 1972, Bell Laboratories, in Chester, New Jersey, conducted research trying to develop a method of steering and tracking moles.
- a 4-inch Schramm Pneumagopher was fitted with two steering fins and three mutually orthogonal coils which were used in conjunction with a surface antenna to track the position of the tool.
- One of these fins was fixed and inclined from the tool's longitudinal axis while the other fin was rotatable.
- Two boring modes could be obtained with this system by changing the position of the rotatable fin relative to the fixed fin. These were (1) a roll mode in which the mole was caused to rotate about its longitudinal center line as it advanced into the soil and (2) a steering mode in which the mole was directed to bore in a curved path.
- the roll mode was used for both straight boring and as a means for selectively positioning the angular orientation of the fins for subsequent changes in the bore path.
- Rotation of the mole was induced by bringing the rotatable fin into an anti-parallel alignment with the fixed fin. This positioning results in the generation of a force couple which initiates and maintains rotation.
- the steering mode was actuated by locating the rotatable fin parallel to the fixed fin. As the mole penetrates the soil, the outer surfaces of the oncoming fins are brought into contact with the soil and a "slipping wedge” mechanism created. This motion caused the mole to veer in the same direction as the fins point when viewed from the back of the tool.
- Typical well surveying equipment utilizes magnetometers, inclinometers and inertial guidance systems which are complex and expensive.
- the wells drilled are substantially vertical.
- Bell Telephone Laboratories Incorporated has designed a system for boring horizontal holes wherein the direction of drilling is controlled by deploying a three wire antenna system on the surface of the earth and detecting the position and attitude of the drilling tool in respect thereto by pickup coils on the tool. The signals detected are then used to develop control signals for controlling the steering of the tool. See, for example, MacPherson United States Patent No. 3, 656,161. Such control systems have been relatively expensive, and it is no always easy or convenient to deploy the antenna , for example, over a busy highway.
- Steering control is also known in controlling vehicles, aircraft and missiles.
- a radio beacon is used for guidance, the aircraft simply following a beacon to a runway.
- utilities e.g., electric or telephone lines, TV cable, gas distribution piping, or the like
- Another object of this invention is to provide a steering system which will enable a horizontal boring tool to travel over great distances and reliably hit a small target
- Another object of this invention is to provide boring tool which will produce a guided borehole to avoid obstacles and to correct for deviations from the planned boring path.
- Another object of this invention is to provide a boring tool immune to adverse environmental conditions and which allows the boring operation to be conducted by typical field service crews.
- a still further object of this invention is to provide a guided horizontal boring tool which requires a minimal amount of excavation for launching and retrieval and thereby reducing the disturbance of trees, shrubs or environmentally sensitive ecosystems.
- Another object of this invention is to provide a horizontal tool having reduced friction during turning and arcuate movement
- Another object of this invention is to provide a boring tool which is constructed to permit transmittal of the impact force of the tool to the soil while permitting free rotation of the tool.
- Another object of this invention is to provide a boring tool with overgage body sections permitting a 2-point contact (front and rear) of the outer housing of the tool with the soil wall as opposed to the line contact which occurs without the undercut.
- Another object of the invention is to provide a percussion boring tool having a body surface configuration permitting the tool to bore in an arc without distorting the round cross-sectional profile of the pierced hole.
- a further object of this invention is to provide a percussion boring tool having a construction in which a higher rate of turning is possible for a given steering force at the front and/or back of the tool since a smaller volume of soil needs to be displaced.
- a still further object of this invention is to pro vide an improved control system for monitoring and controlling the direction of a percussion boring tool.
- a guided horizontal boring tool constructed in accordance with the present invention will benefit utilities and rate payers by significantly reducing installation and maintenance costs of underground utilities by reducing the use of expensive, open-cut trenching methods.
- the above noted objects and other objects of the invention are accomplished by an improved steering system for percussion boring tools.
- the steering mechanism comprises a slanted-face nose member attached to the anvil of the tool to produce a turning force on the tool and movable tail fins incorporated into the trailing end of the tool which are adapted to be selectively positioned relative to the body of the tool to negate the turning force.
- Turning force may also be imparted to the tool by an eccentric hammer which delivers an off-axis impact to the tool anvil.
- the fins also allow the nosepiece to be oriented in any given plane for subsequent turning or direction change.
- the percussion boring tool may optionally have a cylindrical body with overgage sleeves located over a portion of the outer body affixed so that they can rotate but cannot slide axially.
- the overgage areas at the front and back of the tool, or alternately, an undergage section in the center of the tool body permits a 2-point contact (front and rear) of the outer housing with the soil wall as opposed to the line contact which occurs without the undercut.
- the 2-point contact allows the tool to deviate in an arc without distorting the round cross-sectional profile of the pierced hole.
- the control system for a percussion boring tool includes a coil disposed on the tool and energized at relatively low frequency to provide a varying magnetic field extending axially from the tool and providing lines of magnetic flux substantially symmetrically disposed about the tool axis.
- First and second pickup coils are disposed at a distance from the tool. These coils have respective axes at a substantial angle with respect to each other and are mounted to sense the changing flux linked thereby and produce respective first and second electrical signals.
- the coil arrangement provides respective null signals when the respective axes of the pickup coils lie substantially perpendicular to the tool axis and the coils are balanced about the tool axis. The signals therefore indicate the attitude of the tool relative to the coils.
- a third pickup coil may be used to sense the range of the tool when the third coil has an axis extending generally toward the tool, with its output used to normalize the detection signals.
- the axes of the three coils are preferably at angles of 90° from each other.
- the signals from the respective pickup coils may be used to determine the attitude of the tool relative to the pickup coils, and the information used to control the steering mechanism of he tool. This may be done automatically. Because this is a null-based system, the control signal may simply operate the steering mechanism to turn the tool the reduce the deviation from null. This causes the system to be a homing device, like a beacon, -and directs the tool along a path to the coils.
- the system may then direct the tool out of the path, around an obstacle, and back on course.
- an important aspect of the present invention is to provide a null detection system to determine the attitude of a horizontal boring tool relative to detection coils and for controlling the steering of the tool. Another aspect is to provide a control system for such a tool wherein the tool may be steered to home in on the detection coils.
- a preferred guided horizontal boring tool 10 used with a magnetic field attitude sensing system.
- the boring tool 10 may be used with various sensing systems, and a magnetic attitude sensing system is depicted generally as one example.
- the usual procedure for using percussion moles is to first locate and prepare the launching and retrieval pits.
- the launching pit P should be dug slightly deeper than the planned boring depth and large enough to provide sufficient movement for the operator.
- the mole or boring tool 10 is connected to a pneumatic or hydraulic source 11, is then started in the soil, stopped and properly aligned, preferably with a sighting frame and level.
- the tool is then restarted and boring continued until the tool exits into the retrieval pit (not shown).
- the boring tool 10 may have a pair of coils 12 at the back end, one of which produces a magnetic field parallel to the axis of the tool, and the other produces a magnetic field transverse to the axis of the tool. These coils are intermittently excited by a low frequency generator 13. To sense the attitude of the tool, two coils 14 and 15 are positioned in the pit P, the axes of which are perpendicular to the desired path of the tool. The line perpendicular to the axes of these coils at the coil intersection determines the boresite axis.
- Outputs of these coils can be processed to develop the angle of the tool in both the horizontal and vertical directions with respect to the boresite axis.
- the same set of coils can be utilized to determine the angular rotation of the tool to provide suffi+cient control for certain types of steering systems. For these systems, the angular rotation of the tool is displayed along with the plane in which the tool is expected to steer upon actuation of the guidance control system.
- the mechanical guidance of the tool can also be controlled at a display panel 16. From controls located at display panel 16, both the operation of the tool 10 and the pneumatic or hydraulic actuation of the fins 17 can be accomplished as described hereinafter.
- the boring tool 10 includes a steering system with a slanted-face nose member 18 attached to the anvil 33 of the tool to produce a turning force on the tool and tail fins 17 on a rotary housing 19 on the trailing end of the tool adapted to be selectively positioned relative to the body of the tool to negate the turning force.
- Turning force may also be imparted to the tool by an internal eccentric hammer (Fig. 41) described hereinafter which delivers an off-axis impact to the tool anvil.
- the tail fins 17 are moved into a position where they may spin about the longitudinal axis of the tool 10 and the slanted nose member 18 or eccentric hammer will deflect the tool in a given direction.
- the rotation will negate the turning effect of the nose member 18 or eccentric hammer as well as provide a means for orienting the nose piece into any given plane for subsequent turning or direction change.
- an eccentric hammer or anvil will produce the desired turning force, since the only requirement is that the axis of the impact does not pass through the frontal center of pressure.
- the steering system of the present invention will allow the operator to avoid damaging other underground serv ices (such as power cables) or to avoid placing underground utilities where they may be damaged.
- Figs. 2 through 7 illustrate various combinations and implementations of the combination slanted nose member and tail fins steering system - schematically and illustrates the basic operation of each design.
- the function of the tail fins is to provide a method of executing controlled changes to the boring direction.
- a fixed/lockable tail fin steering system 17 is illustrated in Figs. 2 and 3.
- the tool is allowed to rotate about the longitudinal axis due to the turning force of the tail fins when in the locked position until the proper tool face orientation is obtained (Fig. 2).
- the housing 19 is then unlocked and spins freely, whereby the tool moves in a curved path by the turning force of the slanted face nose member 18.
- Straight boring by the tool 10 is accomplished by locking tail fin housing 19 to the main body 20 of the tool 10 (Fig. 3), to rotate the tool body and thus negate the turning action of the slanted nose member 18.
- a boring tool 21 having a movable tail fin system is illustrated in Figs. 4 -7.
- the tail fins 22 are activated to a parallel position relative to the longitudinal axis of the tool body 20 and the tool 21 is allowed to turn relative to the longitudinal axis due to the turning force of the nose member 18 or the eccentric hammer.
- Proper tool face orientation is obtained (Figs. 4 and 5) by use of the tail fins in a skewed inclined position.
- Straight boring of the tool is accomplished by activating the fins 22 to an inclined position relative to the mole axis (Figs. 6 and 7) to rotate the tool body and thus negate the turning action of the slanted nose member 18.
- Fig. 8 illustrates a boring tool 23 with a movable tail fin system in combination with an eccentric hammer 24.
- the eccentric hammer may be used in combination with either the fixed/lockable fin system or the movable fin system and with or without the slanted nose member, depending upon the particular application. Either an eccentric hammer or anvil will produce the desired result, since the only requirement is that the axis of the impact does not pass through the frontal center of pressure. Unless negated by one of the previously described fin systems, the eccentric hammer 24 provides the side force required to turn the tool.
- the eccentric hammer 24 is keyed to the main body 25 of the tool 23 by a pin 26 or other suitable menas to maintain the larger mass of the hammer on one side of the longitudinal axis of the tool.
- Turning of the tool 23 is accomplished by unlocking the tail fin housing of the fixedflockable embodiment from the main mole body or turning the fins of the movable fin embodiment to a position parallel to the body axis.
- the parallel fins or unlocked housing position eliminates the fins ability to negate the eccentric hammer force.
- the tail fin housing is unlocked or the fins are activated to a skewed inclined position relative to the tool body axis and the tool is turned by the eccentric hammer force until the proper tool face orientation is obtained.
- Straight boring is accomplished in all of the previously described implementations by continuously rotating the tool. This distributes the turning force over 360° and causes the tool to bore a helical (nearly straight) hole.
- Figs. 9A, 9B, 9C, and 10 illustrate a typical boring tool 27 having a slanted nose member and fixedllockable fin arrangement as described generally in reference to Figs. 1 and 2.
- the boring tool 10 comprises an elongated hollow cylindrical outer housing or body 28.
- the outer front end of the body 28 tapers inwardly forming a conical portion 29.
- the internal diameter of the body 28 tapers inwardly near the front end forming a conical surface 30 which terminates in a reduced diameter 31 extending longitudinally inward from the front end.
- the rear end of the body 28 has internal threads 32 for receiving a tail fin assembly (see Fig. 9C).
- An anvil 33 having a conical back portion 34 and an elongated cylindrical front portion 35 is positioned in the front end of body 28.
- the conical back portion 34 of anvil 33 forms an interference fit on the conical surface 30 of the body 28, and the elongated cylindrical portion 35 extends outwardly a predetermined distance beyond the front end of the body.
- a flat transverse surface 36 at the back end of anvil 33 receives the impact of a reciprocating hammer 37.
- Reciprocating hammer 37 is an elongated cylindrical member slidably received within the cylindrical recess 38 of the body 28. A substantial portion of the outer diameter of the hammer 28 is smaller in diameter than the recess 38 of the body 28, forming an annular cavity 39 therebetween. A relatively shorter portion 40 at the back end of the hammer 37 is of larger diameter to provide a sliding fit against the interior wall of recess 38 of the body 28.
- a central cavity 41 extends longitudinally inward a distance from the back end of the hammer 37.
- a cylindrical bushing 42 is slidably disposed within the hammer cavity 41, the circumference of which provides a sliding fit against the inner surface of the central cavity 41.
- the front surface 43 of the front end of the hammer 37 is shaped to provide an impact centrally on the flat surface 36 of the anvil 33. As described hereinafter, the hammer configuration may also be adapted to deliver an eccentric impact force on the anvil.
- An air distribution tube 45 extends centrally through the bushing 42 and has a back end 46 extending outwardly of the body 28 connected by fittings 47 to a flexible hose 48.
- the air distribution tube 45 is in permanent communication with a compressed air source 11 (Fig. 1).
- the arrangement of the passages 44 and the bushing 42 is such that, during reciprocation of the hammer 37, the air distribution tube 45 alternately communicates via the passages 44, the annular cavity 39 with either the central cavity 41 or atmosphere at regular intervals.
- a cylindrical stop member 49 is secured within the recess 38 in the body 28 near the back end and has a series of longitudinally-extending, circumferentially-spaced passageways 50 for exhausting the interior of the body 28 to atmosphere and a central passage through which the air distribution tube 45 extends.
- a slant-end nose member 18 has a cylindrically recessed portion 52 with a central cylindrical bore 53 therein which is received on the cylindrical portion 35 of the anvil 33 (Figs. 9A and 10).
- a slot 54 through the sidewall of the cylindrical portion 18 extends longitudinally substantially the length of the central bore 53 and a transverse slot extends radially from the bore 53 to the outer circumference of the cylindrical portion, providing flexibility to the cylindrical portion for clamping the nose member to the anvil.
- a flat 56 is provided on one side of cylindrical portion 18 and longitudinally spaced holes 57 are drilled therethrough in alignment with threaded bores 58 on the other side. Screws 59 are received in the holes 57 and bores 58 and tightened to secure the nose member 18 to the anvil 33.
- the sidewall of the nose member 18 extends forward from the cylindrical portion 52 and one side is milled to form a flat inclined surface 60 which tapers to a point at the extended end.
- the length and degree of inclination may vary depending upon the particular application.
- the nose member 18 may optionally have a flat rectangular fin 61 (shown in dotted line) secured to the sidewall of the cylindrical portion 52 to extend substantially the length thereof and radially outward therefrom in a radially opposed position to the inclined surface 60.
- Slanted nose members 18 of 2-1/2" and 3-1/2" diameter with angles from 10° to 40° have been tested and show the nose member to be highly effective in turning the tool with a minimum turning radius of 28 feet being achieved with a 3-1/2 inch 15 degree nose member. Testing also demonstrated that the turning effect of the nose member was highly repeatable with deviations among tests of any nose member seldom varying by more than a few inches in 35 feet of bore. Additionally, the slanted nose members were shown to have no adverse effect on penetration rate and in some cases actually increased it.
- the turning radius varies linearly with the angle of inclination. For a given nose angle, the turning radius will decrease in direct proportion to an increase in area.
- a tail fin assembly 19 is secured in the back end of the body 28 (Fig. 9C).
- a fixed/lockable tail fin assembly 19 is illustrated in the example and other variations will be described hereinafter.
- the tail fin assembly 19 comprises a cylindrical connecting sub 63 having external threads 64 at the front end which are received within the internal threads 32 at the back end of the body 28.
- Sub 63 has a short reduced outside diameter portion 65 forming shoulder 66 therebetween and a second reduced diameter 67 adjacent the short portion 65 forms a second shoulder 68.
- An O-ring seal 69 is located on the reduced diameter 65 intermediate the shoulders 66 and 68.
- the rear portion 70 of the sub 63 is smaller in diameter than the second reduced diameter 67 forming a third shoulder 71 therebetween and provided with a circumferential 0-ring seal 72 and an internal 0-ring seal 73.
- Internal threads 74 are provided in the rear portion 70 inwardly of the seal 73.
- a circumferential bushing 75 of suitable bearing material such as bronze is provided on the second reduced diameter 67.
- a series of longitudinal circumferentially spaced grooves or keyways 76 are formed on the circumference of the rear portion 70 of the sub 63.
- a hollow cylindrical piston 77 is slidably received on the circumference of the rear por tion 70.
- a series of longitudinal circumferentially spaced grooves or keyways 78 are. formed on the interior surface at the front portion of the piston 77 in opposed relation to the sub keyways 76.
- a series of keys or dowel pins 79 are received within the keyways 76 and 78 to prevent rotary motion between the sub 63 and the piston 77.
- a first internal cavity 80 extends inwardly from the keyway 78 terminating in a short reduced diameter portion 81 which forms a shoulder 82 therebetween.
- a second cavity 83 extends inwardly from the back end 84 of the piston 77 terminating at the reduced diameter portion 81.
- An internal annular 0- ring seal 85 is provided on the reduced diameter portion 81.
- a series of drive teeth 86 are formed on the back end of the piston 77.
- the teeth 86 comprise a series of circumferentially spaced raised surfaces 87 having a straight side 88 and an angularly sloping side 89 forming a one-way ratchet configuration.
- a compression spring 90 is received within the first cavity 80 of the piston 77 and is compressed between the back end 70 of the sub 63 and the shoulder 82 of the piston 77 to urge the piston outwardly from the sub.
- An elongated, hollow cylindrical rotating fin sleeve 91 is slidably and rotatably received on the outer periphery of sub 63.
- the fin sleeve 91 has a central longitudinal bore 92 and a short counterbore 93 of larger diameter extending inwardly from the front end and defining an annular shoulder 94 therebetween.
- the counterbore 93 fits over the short reduced diameter 65 of the sub 63 with the O-ring 69 providing a rotary seal therebetween.
- a flat annular bushing 95 of suitable bearing material such as bronze is disposed between the shoulders 68 and 94 to reduce friction therebetween.
- a second counterbore 96 extends inwardly from the back end of the fin sleeve 91.
- a hollow cylindrical sleeve 97 is secured within the second counterbore by suitable means such as welding.
- the sleeve 97 has a central bore 98 substantially the same diameter as the second cavity 83 of the piston 77 and a counterbore 99 extending inwardly from the back end defining shoulder 100 therebetween.
- a series of drive teeth 101 are formed on the front end of the sleeve 97.
- the teeth 101 comprise a series of circumferentially spaced raised surfaces 102 having a straight side 103 and an angularly sloping side 104 forming a one-way ratchet configuration.
- the teeth correspond in opposed relationship to the teeth 86 of the piston 77 for operative engagement therewith.
- a series of flat radially and angularly opposed fins 105 are secured to the exterior of the fin sleeve 91 to extend radially outward therefrom. - (Figs. 9C, 11 and 12) The fins 105 are secured at opposing angles relative to the longitudinal axis of the sleeve 91 to impart a rotational force on the sleeve.
- An elongated hollow cap sleeve 106 having external threads 107 at the front end is slidably received within the sliding piston 77 and the sleeve 97 and threadedly secured in the internal threads 74 at the rear portion 70 of the sub 63.
- the cap sleeve 106 extends rearwardly from the threads 107 and an enlarged diameter portion 108 forms a first shoulder 109 spaced from the threaded portion and a second enlarged diameter 110 forms a second shoulder 111 spaced from the first shoulder.
- An O-ring seal 112 is provided on the enlarged diameter 108 near the shoulder 109 and a second O-ring seal 113 is provided on the second enlarged diameter 110 near the second shoulder 111.
- the O-ring 112 forms a reciprocating seal on the interior of the second cavity 83 of the piston 77 and the O-ring 113 forms a rotary seal on the counterbore 99 of the sleeve 97.
- the 0-ring 85 in the piston 77 forms a reciprocating seal on the extended sidewall of the cap 106.
- An annular chamber 114 is formed between the exterior of the sidewall of the cap 106 and the second counterbore 83 which is sealed at each end by the 0-rings 85 and 112.
- a circumferential bushing 115 is provided on the first enlarged diameter 108 and an annular bushing 116 on the second enlarged diameter 110 is captured between the shoulders 110 and 111 to reduce friction between the sleeve 97 and the cap 106.
- the rear portion of the cap 106 has small bores 117 arranged to receive a spanner wrench for effecting the threaded connect ion.
- a threaded bore 118 at the back end of the cap 106 receives a hose fitting (not shown) and a small passageway 119 extends inwardly from the threaded bore 118 to communicate the annular chamber 114 with a fluid or air source (not shown).
- a flexible hose extends outwardly of the cap 106 and is connected to the fluid or air source for effecting reciprocation of the piston 77.
- a second small passageway 120 communicates the first cavity 80 with atmosphere to relieve pressure which might otherwise become trapped therein. Passage 120 may also be used for application of pressure to the forward end of the piston 77 for return movement
- Figs. 14 and 15 The operation of the percussion boring roo ⁇ 27 is illustrated schematically in Figs. 14 and 15. Under action of compressed air or hydraulic fluid in the central cavity 41, the hammer 37 moves toward the front of the body 28. At the foremost position, the hammer imparts an impact on the flat surface 36 of the anvil 33.
- the hammer 37 continues its movement by the expansion of the the air in the annular cavity 39 until the passages 44 are displaced beyond the ends of the bushing 42, and the annular cavity exhausts to atmosphere through the holes 50 in the stop member 49. In this position, the air is exhausted from the annular cavity 39 through the passages 44 now above the trailing edge of the bushing 42 and the holes 50 in the stop member 49. Then the cycle is repeated.
- the operation of the tail fin assembly 62 is best seen with reference to Figs. 9C and 11.
- the compressed air or fluid in the annular cavity 114 moves the piston 77 against the force of the spring 90 and toward the front of the sub 63.
- the front end of the piston 77 contacts the shoulder 71 and the drive teeth 86 and 101 become dis-engaged.
- compressed air or fluid is admitted through the passage 119 from the source into the annular chamber 114.
- the fin sleeve 91 is then free to rotate relative to the tool body.
- the force of the spring 90 moves the piston 77 in the opposite direction (Fig. 11).
- the drive teeth 86 and 101 become engaged once again and the fin sleeve 91 becomes locked against rotational movement relative to the tool body.
- Pressure which may otherwise become trapped in the first cavity 80 and hinder reciprocation is exhausted through the pressure relief passage 120 to atmosphere.
- the cycle may be selectively repeated as necessary for proper alignment the slanted nose member 18 and attitude adjustment of the tool.
- the passage 120 may also be connected to a fluid, i.e. liquid or air, source for moving the piston to the rearward position.
- the tail fin assembly 119 comprises a cylindrical connecting sub 163 having external threads 164 at the front end which are received within the internal threads 32 at the back end of the body 28.
- Sub 163 has a short reduced outside diameter portion 165 forming a shoulder 166.
- the rear portion 170 of the sub 163 is smaller in diameter than the reduced diameter 165 forming a third shoulder 171 therebetween and provided with a circumferential 0-ring seal 172.
- a series of longitudinal circumferentially-spaced grooves or keyways 176 are formed on the rear portion 170 of the sub 163.
- a hollow cylindrical piston 177 is slidably received on the circumference of the rear portion 170.
- a series of longitudinal circumferentially spaced grooves or keyways 178 are formed on the interior surface at the front portion of the piston 177 in opposed relation to the sub keyways 176.
- a series of keys or dowel pins 179 are received within the keyways 176 and 178 to prevent rotary motion between the sub 163 and the piston 177.
- a first internal cavity 180 extends inwardly from the keyway 178 terminating in a short reduced diameter portion 181 which forms a shoulder 182 therebetween.
- a second cavity 183 smaller than the first extends inwardly from the back end 184 of the piston 77 terminating at the reduced diameter portion 181.
- O-ring seals 173 and 185 are provided on the interior of the first cavity 180 and reduced diameter portion 181 respectively.
- a series of drive teeth 86 are formed on the back end of the piston 177.
- the teeth 86 comprise a series of circumferentially spaced raised surfaces 87 having a straight side 88 and an angularly sloping side 89 forming a one-way ratchet configuration.
- An elongated hollow cylindrical rotating fin sleeve 191 is rotatably received on the outer periphery of the sub 163.
- the fin sleeve 191 has a central longitudinal bore 192.
- the bore 192 is rotatably received on the reduced diameter 165 of the sub 163 with the O-ring 169 providing a rotary seal therebetween.
- a flat annular bushing 195 of suitable material such as bronze is disposed between the shoulder 168 and the front of the fin sleeve 191 to reduce friction.
- a hollow cylindrical sleeve 197 is secured within the rear portion of the fin sleeve bore 192 by suitable means such as welding.
- the sleeve 197 has a central bore 198 substantially the same diameter as the second cavity 183 of the piston 177.
- a series of drive teeth 101 are formed on the front end of the sleeve 197.
- the teeth 101 comprise a series of circumferentially spaced raised surfaces 102 having a straight side 103 and an angularly sloping side 104 forming a one-way ratchet configuration.
- the teeth correspond in opposed relationship to the teeth 86 of the piston 177 for operative engagement therewith.
- An O-ring 213 and a bushing 215 are provided in the central bore 198.
- a series of flat, radially and angularly opposed fins 205 are secured to the exterior of the fin sleeve 191 to extend radially outward therefrom.
- the fins 205 are secured at opposing angles relative to the longitudinal axis of the sleeve 191 to impart a rotational force on the sleeve.
- An elongated hollow cylindrical cylinder cap 206 having external threads 207 at the front end is slidably received within the sliding piston 177 and the sleeve 197 and threadedly secured in the internal threads 174 at the rear portion 170 of the sub 163.
- the circumference of the cap 206 extends rearwardly from the threads 207 and an enlarged diameter portion 208 forms first shoulder 209 spaced from the threaded portion and a second enlarged diameter 210 forms second shoulder 211 spaced from the first shoulder.
- An O-ring seal 212 is provided on the enlarged diameter 208 near the shoulder 209.
- the O-ring 212 forms a reciprocating seal on the interior of the second cavity 183 of the piston 177 and the O-ring 213 forms a rotary seal on the central bore 198 of the sleeve 197.
- the O-ring 185 in the piston 177 forms a reciprocating seal on the extended sidewall of the cap 206.
- An annular rear chamber 214 is formed between the exterior of the sidewall of the cap 206 and the second smaller bore 183 which is sealed at each end by the 0-rings 185 and 212.
- An annular front chamber 216 is formed between the sidewall of the cap 206, the cavity 180, and the back end of the sub 163, which is sealed by the 0-rings 172, 173, and 185.
- the side wall of the sub 163 has small bores 217 arranged to receive a suitable wrench for effecting the threaded connection.
- a threaded bore 218 at the back end of the cap 206 receives a hose fitting (not shown) and a small passageway 219 extends inwardly from the threaded bore 218 to communicate the rear chamber 214 with a fluid or air source (not shown).
- Another similar threaded bore at the back end of the cap receives a hose fitting (not shown) and a small passageway 220 extends inwardly from the threaded bore to communicate the front chamber 216 with a fluid or air source (not shown).
- Flexible hoses extend outwardly of the cap 206 and are connected to the fluid or air source for effecting reciprocation of the piston 177.
- the operation of the tail fin assembly 119 is illustrated schematically in Figs. 16 and 17.
- the piston 177 moves toward the front of the sub 163.
- the drive teeth 86 and 101 are disengaged and the fin sleeve 191 is free to rotate about the longitudinal axis of the tool body.
- compressed air or fluid in the front chamber 216 has been exhausted.
- compressed air or fluid is admitted through the passage 220 into the front chamber 216 and exhausted from the rear chamber 214 to move the piston 177 in the opposite direction.
- the drive teeth 86 and 101 are once again engaged preventing rotational movement.
- the cycle may be selectively repeated as necessary for proper alignment the slanted nose member and attitude adjustment of the tool.
- FIG. 18 Another variation of the fixedllockable tail fin assembly having drive teeth is illustrated in Figs. 18 and 19. To avoid repetition, some of the components, details, and reference numerals previously shown and described with reference to Figs. 9C and 11 will not be repeated here. Other components previously described will carry the same numerals of reference.
- the tail fin assembly 219 comprises a cylindrical connecting sub 263 having external threads at the front end which are received within the internal threads at the back end of the body.
- the sub 263 has a short reduced diameter portion forming a first shoulder. and a second reduced diameter adjacent the short portion forms a second shoulder.
- An annular O-ring seal is provided on the first reduced diameter intermediate the first and second shoulders.
- the sidewall of the sub 263 extends rearwardly from the second shoulder.
- the rear portion 270 of the sub 263 is smaller in diameter than the second reduced diameter forming a third shoulder 268 and a forth reduced diameter defines a fourth shoulder 271.
- a circumferential O-ring seal 272 is provided at back end of the sub 263. External threads 274 are provided in the rear portion 270 inwardly of the seal 272
- a series of circumferentially spaced spherical apertures 276 are formed on the circumference of the sidewall of the sub 263 near the third shoulder 271 and carry a series of balls 279.
- a hollow cylindrical piston 277 is slidably received on the circumference of the rear portion 270.
- a ser ies of longitudinal circumferentially spaced grooves or keyways 278 are formed on the interior surface at the front portion of the piston 277 in opposed relation to the balls 279. The balls 279 within apertures 276 and keyways 278 prevent rotary motion between sub 263 and piston 277.
- a first cavity 280 extends inwardly from the front end of the piston 277 and terminates in a short reduced diameter portion 281 which forms a shoulder 282.
- a second cavity 283 extends inwardly from the back end of the piston 277 terminating at the reduced diameter portion 281.
- An 0- ring seal 285 is provided on the reduced diameter portion 281.
- a series of drive teeth 86 are formed on the back end of the piston 277.
- the teeth 86 comprise a series of circumferentially spaced raised surfaces 87 having a straight side 88 and an angularly sloping side 89 forming a one-way ratchet configuration.
- a compression spring 290 surrounds the sidewall of the sub 263 and the ends of the spring are biased against the shoulder 268 of the sub 270 and the front end of the piston 277 to urge the piston outwardly from the sub.
- a hollow cylindrical rotating fin sleeve 291 having a rear counterbore 296 is slidably and rotatably received on the outer periphery of sub 263.
- a hollow cylindrical sleeve 297 is secured within the second counterbore 296 by suitable means such as welding.
- the sleeve 297 has a central bore substantially the same diameter as the second cavity 283 of the piston 277.
- a series of drive teeth 101 are formed on the front end of the sleeve 297.
- the teeth 101 comprise a series of circumferentially spaced raised surfaces 102 having a straight side 103 and an angularly sloping side 104 forming a one-way ratchet configuration.
- the teeth correspond in opposed relationship to the teeth 86 of the piston 277 for operative engagement therewith.
- a series of flat radially and angularly opposed fins as previously described are secured to the exterior of the fin sleeve to extend radially outward therefrom.
- An elongated hollow cylindrical cylinder cap 306 having internal threads 307 at the front end is slidably received within the sliding piston 277 and the sleeve 297 and threadedly secured on the external threads 274 at the rear portion 270 of the sub 263.
- An 0-ring seal 312 is provided on the outer front portion of cap 306 and a second O-ring. seal 313 is provided on the rear portion.
- the O-ring 312 forms a reciprocating seal on the interior of cavity 283 of piston 277 and O-ring 313 forms a rotary seal on the counterbore of fin sleeve 291.
- the 0-ring 285 in piston 277 forms a reciprocating seal on the sidewall of cap 306.
- An annular chamber 314 is formed between the exterior of the sidewall of the cap 306 and the counterbore 283 which is sealed at each end by the O-rings 285 and 312. Bushings as previously described are provided on the sub 263 and cylinder cap 306 to reduce friction therebeween.
- the rear portion of the cap has a threaded bore 318 at the back end of the cap 306 which receives a hose fitting (not shown) and a small passageway 319 extends inwardly from the threaded bore 318 to communicate the annular chamber 314 with a fluid or air source (not shown).
- a flexible hose extends outwardly of the cap 306 and is connected to the fluid or air source for effecting reciprocation of the piston 277.
- the operation of the tail fin assembly 219 is best seen with reference to Figs. 18 and 19.
- Compressed air or fluid in the annular cavity 314 moves the piston 277 to overcome the force of the spring 290 and move toward the front of sub 263.
- the drive teeth 86 and 101 - become disengaged.
- compressed air or fluid is admitted through the passage 319 from the source into the annular chamber 314.
- the fin sleeve 291 is then free to rotate relative to the tool body.
- Figs. 20 and 21 are longitudinal cross sections of an alternate embodiment of the fixed/lockable fin assembly which incorporates a drive pin arrangement in place of one of the drive teeth members previously described. It will be noted that the drive pin arrangement necessitates moving the fin sleeve along the longitudinal axis to effect fin positioning.
- the tail fin assembly 400 comprises a cylindrical connecting sub 401 having external threads 402 at the front end which are received within the internal threads 32 at the rear portion of the body 28.
- the sub 401 has a first reduced diameter portion 403 forming a first shoulder 404 and a second reduced diameter 405 adjacent the first forms a second shoulder 406 which receives an annular seal 407.
- the rear portion 408 of sub 401 is smaller in diameter than the second reduced diameter 405 and extends longitudinally therefrom.
- a thin cylindrical retainer ring 409 is secured on the first reduced diameter 403 of the sub 401 by screws 410 and a small annular rib 411 on the interior surface of the ring captures the seal 407 within the second shoulder 406.
- the rear end of ring 409 extends a short distance beyond seal 407 to surround the forward end of the rear portion 408 of the sub 401.
- An elongated, hollow cylindrical rotating fin sleeve 412 is slidably and rotatably received within the extended portion of ring 409 and surrounds the rear portion 408 of sub 401.
- the fin sleeve 412 has a central longitudinal bore 413 and a counterbore 414 of large diameter extending inwardly from the back end and defining an annular shoulder 415 therebetween.
- An O-ring seal 416 on fin sleeve 412 provides a rotary and reciprocating seal on the inner surface of ring 409.
- a plurality of circumferentially spaced dowel pins 417 extend radially inwardly through the side wall of the fin sleeve 412 and terminate a short distance from the circumference of the rear portion 408 to the sub 401.
- An annular 0-ring seal 418 and a bushing 419 is provided on the interior surface of the fin sleeve 412 intermediate the dowel pins 417 and shoulder 415.
- a series of radially and angularly opposed fins 420 are secured to the exterior of the rotating fin sleeve 412 to extend radially outward therefrom.
- the fins are secured at opposing angles relative to the longitudinal axis of the sleeve 412 to impart a rotational force on the sleeve.
- An elongated hollow cylindrical cap 421 is slidably received on the sub rear portion 408 within fin sleeve 412 and secured to sub 401 by means of a screw 422 at the rear portion thereof.
- the cap 421 has a reduced diameter front portion 423 and an enlarged diameter rear portion 424 forming a shoulder 425.
- a pair of longitudinally spaced O-rings 426 are positioned on the rear portion 424 and a bushing 427 is provided intermedi ate the O-rings 426.
- the enlarged diameter rear portion 424 of the cap 421 is rotatably received within counterbore 414 with the O-rings 426 providing a rotary seal therebetween.
- a series of drive teeth 428 are formed on the front end of the cap 421.
- the drive teeth 428 comprise a series of circumferentially spaced raised surfaces 429, each having a generally straight side 430 and an angularly sloping side 431 forming a one-way ratchet configuration.
- the spacing of the drive teeth 428 relative to the dowel pins 417 is such that the pins will be retained by the teeth in the locked position to prevent rotary motion between the fin sleeve 412 and cap 421 as described hereinafter.
- annular chamber 432 When properly positioned, an annular chamber 432 is formed between the shoulder 415 of the fin sleeve and the shoulder 425 of the cap sealed at each end by the O-rings 418 and 426.
- a threaded bore 433 at the back end of the cap 421 receives a hose fitting (not shown) and a small passageway 434 extends inwardly from the threaded bore to communicate the annular chamber 432 with a fluid or air source (not shown) for reciprocating fin sleeve 412.
- the driving force of the tool hammer carries the tool including the cap 421 forward (Fig. 21).
- drive teeth 428 and dowel pins 417 become engaged once again and fin sleeve 412 becomes locked against rotatianal movement relative to the tool body.
- the cycle may be selectively repeated as necessary for proper alignment of the slanted nose member and attitude adjustment of the tool.
- Figs. 23 and 24 are partial longitudinal cross sections of variations of the fixed/4ockable fin assembly using a drive pin.
- the tail fin assembly 500 comprises a cylindrical connecting sub 501 having external threads 502 at the front end which are received within the internal threads 32 at the rear portion of the body 28.
- the sub 501 has a first reduced diameter portion 503 forming a shoulder 504.
- the rear portion 505 of the sub 501 is smaller in diameter than the first reduced diameter forming a second shoulder 506.
- the rear portion 505 extends longitudinally from shoulder 506 and has exterior threads 507 at the back end.
- a thin cylindrical retainer ring 508 is received on the reduced diameter 503 of sub 501 by screws 509.
- the rear end of ring 508 extends a short distance beyond the shoulder 506 to surround the forward end of the rear portion 505 of the sub 501.
- An elongated hollow cylindrical rotating fin sleeve is slidably and rotatably received within the extended portion of ring 508 and surrounds the rear portion 505 of sub 501.
- the fin sleeve 510 has a central longitudinal bore 511 and a counterbore 512 of larger diameter extending inwardly from the back end and defining an annular shoulder 513.
- An 0-ring seal 514 on the fin sleeve 510 provides a rotary and reciprocating seal on the inner surface of the ring 508.
- a plurality of circumferentially spaced dowel pins 505 extend radially inwardly through the side wall of the fin sleeve 510 and terminate a short distance from the circumference of the rear portion 505 of the sub 501.
- An 0-ring seal 516 and a bushing 517 are positioned on the interior surface of fin sleeve 410 intermediate the dowel pins 515 and shoulder 513.
- a plurality of radially and angularly opposed fins 518 are secured to the exterior of the rotating fin sleeve 510 and extend radially outward therefrom.
- the fins 518 are secured at opposing angles relative to the longitudinal axis of the sleeve 510 to impart a rotational force on the sleeve.
- a tubular cap 519 having a central bore 520 and a threaded counterbore 521 extending inwardly from the front end is slidably received on the air distribution tube 46 and the sub rear portion 505 within the fin sleeve 510.
- the cap 519 is threadedly received and secured on the threads 507 at the end of the sub 501.
- the cap 519 has a reduced diameter front portion 522 and an enlarged diameter rear portion 523 forming a shoulder 524 therebetween.
- a pair of longitudinally spaced O-rings 525 are provided on the rear portion 523 and a bushing 526 is provided intermediate the O-rings 525.
- the enlarged diameter rear portion 523 of cap 519 is rotatably received within the counterbore 512 with O-rings 525 providing a rotary seal.
- a plurality of drive teeth 428 are formed on the front end of the cap 519.
- the rear portion 523 of the cap 519 has a reduced diameter portion 527 which removably receives a conical cover member 528.
- a plurality of circumferentially spaced longitudinal bores 529 extend through the rear portion of the cap 519 for communicating the interior of the body 28 with atmosphere.
- the drive teeth are constructed and operate as previously described for the other embodiments.
- annular chamber 530 is formed between the shoulder 513 of the fin sleeve and the shoulder 524 of the cap and sealed at each end by the O-rings 516 and 524.
- a threaded bore 433 at the back end of the cap 519 receives a hose fitting (not shown) and a small passage way 434 extends inwardly from the threaded bore to communicate the annular chamber 530 with a fluid or air source (not shown) for effecting reciprocation of the fin sleeve 510.
- the driving force of the tool hammer carries the tool including the cap 519 forward (Fig. 24).
- the drive teeth 428 and dowel pins 515 engage once again and the fin sleeve 510 is locked aginst rotational movement relative to the tool body.
- the cycle may be selectively repeated as necessary for proper alignment of the slanted nose member and attitude adjustment of the tool.
- Figs. 25 and 26 are partial longitudinal cross sectional views of a variation of the fixed/lockable fin assembly using an interlocking lug arrangement to prevent rota tional movement.
- the tail fin assembly 600 comprises a cylindrical connecting sub 601 having external threads at the front end which are received within the internal threads at the rear portion of the body (not shown).
- the circumference of the sub 601 has a first reduced diameter portion 602 forming a first shoulder 603.
- the rear portion 604 of the sub 661 is smaller in diameter than the first reduced diameter 602 forming a second shoulder 605.
- An annular raised surface 606 on the rear portion 604 is spaced rearwardly from the shoulder 605 and provided with a series of circumferentially spaced slots 607 forming a series of raised lugs or splines 608.
- the rear portion 604 extends longitudinally from the lugs 608 and is provided with exterior threads 609 at the back end.
- An annular 0- ring seal 610 is provided on the rear portion 604 inwardly of the threads 609.
- a thin cylindrical retainer ring 508 is received on the first reduced diameter 602 of the sub 601 by screws 509.
- the rear end of the ring 508 extends a short distance beyond the shoulder 605 to surround the forward end of the rear portion 604 of the sub 601.
- An elongated hollow cylindrical rotating fin sleeve 611 is slidably and rotatably received within the extended portion of the ring 508 and surrounds the rear portion 604 of the sub 601.
- the fin sleeve 611 has a central longitudinal bore 612, a front and rear counterbore 613 and 614 respect ively of larger diameter extending inwardly from each end and defining annular shoulders 615 and 616 therebetween.
- An annular O-ring seal 617 and annular bushing 618 are disposed on central bore 612 intermediate the shoulders 615 and 616.
- a reduced diameter 619 is provided on the inner diameter of the front counterbore 613 near the front end and provided with a series of circumferentially spaced slots 620 forming a series of raised lugs or splines 621.
- An O-ring seal 622 on the outer circumference of the fin sleeve 611 provides a rotary and reciprocating seal on the inner surface of the ring 508.
- a plurality of radially and angularly opposed fins 518 are secured to the exterior of the rotating fin sleeve 611 to extend radially outward therefrom.
- the fins 518 are secured at opposing angles relative to the longitudinal axis of the sleeve 611 to impart a rotational force on the sleeve.
- An elongated hollow cylindrical cap 623 having a central bore 624 and a larger threaded bore 625 extending inwardly from the front end is slidably received on the air distribution tube 46 and threadedly secured on the threads 609 at the end of the sub 601.
- the outer circumference of the cap 623 is received within the rear counterbore 614 of the fin sleeve 611.
- a pair of longitudinally spaced annular O-rings 626 are provided on the outer circumference of the cap 623 and a bushing 627 is provided intermediate O-rings 626.
- the outer circumference of the cap 623 is rotatably received within the counterbore 614 with the O-rings 626 providing a rotary seal therebetween.
- the rear portion of the cap 623 has a reduced diameter portion 628 which removably receives a conical cover member 629.
- a plurality of circumferentially spaced longitudinal bores 630 extend through the rear portion of the cap for communicating the interior of the tool body with atmosphere.
- annular chamber 631 is formed between the shoulder 616 of the fin sleeve and the forward end of the cap 623 and sealed at each end by the O-rings 610, 617, and 626.
- a threaded bore 433 at the back end of the cap 623 receives a hose fitting (not shown) and a small passageway 434 extends inwardly from the threaded bore to communicate the annular chamber 631 with a fluid or air source (not shown) for effecting reciprocation of the fin sleeve.
- the operation of the tail fin assembly 600 is best seen with reference to Figs. 25 and 26.
- the fin sleeve 611 Under action of compressed air or fluid in the annular chamber 631 the fin sleeve 611 begins to move toward the front of the sub 601. When in its foremost position, the front end of the sleeve 611 contacts the shoulder 605 and the lugs 608 and 621 become disengaged. In this position (Fig. 25), compressed air or fluid is admitted through the passage 434 from the source into the annular chamber 631. The fin sleeve 611 is then free to rotate relative to the tool body.
- the driving force of the too! hammer carries the tool including the cap 623 forward (Fig. 26).
- the drive lugs or splines 608 and 621 become engaged once again and the fin sleeve 611 becomes locked against rotational movement relative to the tool body.
- the cycle may be selectively movement relative to the tool body. The cycle may be safer-- tivety repeated as necessary for proper alignment of the slanted nose member and attitude adjustment of the tool.
- Figs. 27 and 28 are partial longitudinal cross sections of another variation of the fixedaockable fin assembly using a drive pin.
- the tail fin assembly 650 comprises a cylindrical connecting sub 651 having external threads 652 at the front end which are received within the internal threads 32 at the rear portion of the body 28.
- the rear portion 653 of the sub 651 is smaller in diameter than the front portion forming a shoulder 654.
- the rear portion 653 extends longitudinally from the shoulder 654 and has interior threads 655 at the back end.
- a thin cylindrical retainer ring 656 is received on the front portion of the sub 651 between a raised shoulder 657 and the back end of the body 28.
- the rear end of the ring 656 extends a short distance beyond the raised shoulder 657 to surround the forward end of the rear portion 653 of the sub 651.
- a plurality of circumferentially spaced dowel pins 417 extend radially outward through the side wall of the rear portion 653 and terminate a short distance from the interior surface of the ring 656.
- An elongated hollow cylindrical rotating fin sleeve 659 is slidably and rotatably received within the extended portion of the ring 656 and surrounds the rear portion 653 of the sub 651 including the dowel pins 417.
- the fin sleeve 659 has a central longitudinal bore 660 and a counterbore 661 of larger diameter extending inwardly from the back end and defining an annular shoulder 662 therebetween.
- An O-ring seal 663 on the outer circumference. of the fin sleeve 659 provides a rotary and reciprocating seal on the inner surface of the ring 656.
- An annular O-ring seal 664 and a pair of bushings 665 are provided on the interior surface of the fin sleeve 659.
- a plurality of drive teeth 428 - (as previously shown and described) are formed on the front end of the fin sleeve 659.
- a plurality of radially and angularly opposed fins 666 are secured to the exterior of the rotating fin sleeve 659 to extend radially outward therefrom.
- the fins 666 are secured at opposing angles relative to the longitudinal axis of the sleeve 659 to impart a rotational force on the sleeve.
- An elongated hollow cylindrical cap 667 having a central bore 668 and a counterbore 669 extending inwardly from the front end is slidably received on the air distri bution tube 46 within the fin sleeve 659. Exterior threads 670 are provided on the front portion of the cap 667 which are received on the threads 655 at the back end of the sub 651. The rear portion of the cap 667 is larger in diameter than the threaded front portion forming a shoulder 671 therebetween.
- a pair of longitudinally spaced annular O-rings 672 are provided on the outer circumference of the rear portion and a bushing 673 is provided intermediate the O-rings.
- the enlarged diameter rear portion of the cap 667 is rotatably received within the counterbore 661 with the O-rings 672 providing a rotary seal therebetween.
- the rear portion of the cap 667 removably receives a conical cover member 674.
- annular chamber 675 is formed between the shoulder 662 of the fin sleeve and the shoulder 671 of the cap and sealed at each end by the O-rings 663 and 672.
- a threaded bore 433 at the back end of the cap 667 receives a hose fitting (not shown) and a small passageway 434 extends inwardly from the threaded bore to communicate the annular chamber 675 with a fluid or air source (not- shown) for effecting reciprocation of the fin sleeve 659.
- Fig. 28 shows the locked position, and since the operation of the tail fin assembly has been previously shown and explained, it will not be repeated here.
- Figs. 29 and 30 are partial longitudinal cross sections of another variation of the fixed/lockable fin assembly using a series of slots or splines and dowel pins to prevent rotational movement.
- the tail fin assembly 700 comprises a cylindrical connecting sub 701 having external threads 702 at the front end which are received within the internal threads 32 at the rear portion of the body 28.
- the circumference of the sub 701 has a first reduced diameter portion 703 forming a first shoulder 704 therebetween.
- a second reduced diameter 705 forms a second shoulder 706.
- a third reduced diameter 707 forms a third reduced diameter 708.
- An enlarged diameter 709 approximately the same diameter as the second is spaced therefrom and provided with a series of circumferentially spaced slots 710 defining a series of raised lugs or splines 711 on the third reduced diameter 707.
- a fourth diameter 712 smaller than the third forms a fourth shoulder 714 therebetween.
- the fourth diameter 712 extends longitudinally from the shoulder-714 and is provided with exterior threads 715 at the back end.
- a thin cylindrical retainer ring 716 is received on the first reduced diameter 703 of the sub 701 by screws 717.
- the rear end of the ring 716 extends a short distance beyond the shoulder 706 to surround the forward end of the reduced diameter 705.
- a rod wiper 718 is contained on the interior of the rear end of the ring 716.
- An elongated hollow cylindrical rotating fin sleeve 719 is slidably rotatably received within the extended portion of the ring 716 and surrounds the rear portion of the sub 701.
- the fin sleeve 719 has a central longitudinal bore 720, a front and rear counterbore 721 and 722 respectively of larger diameter extending inwardly from each end and defining annular shoulders 823 and 724 therebetween.
- An annular bushing 725 is disposed on the inner diameter of the counterbore 721 and a rod wiper 726 is provided on the inner diameter of the counterbore 722.
- a plurality of circumferentially spaced dowel pins 727 extend radially inwardly through the side wall of the fin sleeve 719 and terminate a short distance from the circumference of the third reduced diameter 707 of the sub 701.
- An annular bushing 728 is provided on the central bore 720 intermediate the shoulders 723 and 724.
- a plurality of radially and angularly opposed fins 729 are secured to the exterior of the rotating fin sleeve 719 to extend radially outward therefrom.
- the fins 729 are secured at opposing angles relative to the longitudinal axis of the sleeve 719 to impart a rotational force on the sleeve.
- An elongated hollow cylindrical cap 730 having a central bore 731 provided with interior threads 732 and a counterbore 733 extending inwardly from the front end is received on the threads 715 of the sub 701 and within the counterbore 722 of the fin sleeve 719.
- An annular 0-ring 734 on the bore 731 provides a seal on the fourth reduced diameter 712 of the sub 701.
- a cylindrical reciprocating piston 735 is slidably reeived on the fourth reduced diameter 712 of the sub 701 and within the counterbore 733 of the cap 730.
- Annular O-rings 736 and 737 are provided on the inner and outer diameters respectively of the piston 735.
- annular chamber 736 is formed between the fourth reduced diameter 712 and the counterbore 733 and sealed at each end by the 0-rings 734, 736 and 737.
- a threaded bore 433 at the back end of the cap 730 receives a hose fitting (not shown) and a small passageway 434 extends inwardly from the threaded bore to communicate the annular chamber 736 with a fluid or air source (not shown) for effecting reciprocation of the piston 735 and fin sleeve 719.
- the operation of the tail fin assembly 700 is best seen with reference to Figs. 29 and 30.
- the piston 735 Under action of compressed air or fluid in the annular chamber 736 the piston 735 begins to move toward the front of the sub 701 and contacts the shoulder 724 of the fin sleeve 719 carrying it forward.
- the front end of the piston 735 contacts the shoulder 714 and the dowel pins 727 become disengaged from the slots or splines 810.
- compressed air or fluid is admitted through the passage 434 from the source into the annular chamber 736.
- the fin sleeve 719 is then free to rotate relative to the tool body.
- the driving force of the tool hammer carries the tool including the sub 701 forward relative to the fin sleeve 719 (Fig. 24).
- the shoulder 724 moves the piston rearwardly and the dowel pins 727 become engaged once again in the slots 710 and the fin sleeve 719 becomes locked against rotational movement relative to the tool body.
- the cycle may be selectively repeated as necessary for proper alignment of the slanted nose member and attitude adjustment of the tool.
- Figs. 31 and 32 are partial longitudinal cross sections of another variation of the fixed/lockable fin assembly using a series of slots or splines and dowel pins to prevent rotational movement
- the tail fin assembly 750 comprises a cylindrical connecting sub 751 having external threads 752 at the front end which are received within the internal threads 32 at the rear portion of the body 28.
- the circumference of the sub 751 has a first reduced diameter portion 753 forming a first shoulder 754 therebetween.
- a second reduced diameter 755 forms a second shoulder 906.
- a third reduced diameter 757 forms a third shoulder 758.
- An enlarged diameter 759 approximately the same diameter as the second is spaced therefrom and provided with a series of circumferentially spaced slots 760 defining a series of raised lugs or splines 761 on the third reduced diameter 757.
- the third diameter 757 extends longitudinally from the lugs or splines 761 and is provided with exterior threads 762 at the back end.
- a thin cylindrical retainer ring 763 is received on the first reduced diameter 753 of the sub 751 by screws 754.
- the rear end of the ring 763 extends a short distance beyond the shoufder-756 to surround the forward end of the reduced diameter 755.
- a rod wiper 765 is contained on the interior of the rear end of the ring 763.
- An elongated hollow cylindrical rotating fin sleeve 766 is slidably and rotatably received within the extended portion of the ring 763 and surrounds the rear portion of the sub 751.
- the fin sleeve 766 has a central longitudinal bore 767, a front and rear counterbore 768 and 769 respectively of larger diameter extending inwardly from each end and defining annular shoulders 770 and 771 therebetween.
- An annular bushing 772 is disposed on the inner diameter of the counterbore 768 and a rod wiper 773 is provided on the inner diameter of the rear counterbore 769.
- a plurality of circumferentially spaced dowel pins 774 extend radially inwardly through the side wall of the fin sleeve 766 and terminate a short distance from the circumference of the third reduced diameter 757 of the sub 751.
- a plurality of radially and angularly opposed fins 775 are secured to the exterior of the rotating fin sleeve 766 to extend radially outward therefrom.
- the fins 775 are secured at opposing angles relative to the longitudinal axis of the sleeve 766 to impart a rotational force on the sleeve.
- An elongated hollow cylindrical cap 776 having a central bore 777 provided with interior threads 778 and a counterbore 779 extending inwardly from the front end is received on the threads 762 of the sub 751 and within the counterbore 769 of the fin sleeve 766.
- An annular 0-ring 780 on the bore 777 provides a seal on the third reduced diameter 757 of the sub 751.
- An annular bushing 781 is provided on the circumference of the cap 776.
- a cylindrical reciprocating piston 782 is slidably received on the third reduced diameter 757 of the sub 751 and within the counterbore 769 of the cap 776.
- a reduced diameter 783 at the front end of the piston is received within the central bore 767 of the fin sleeve 766.
- Annular O-rings 784 and 785 are provided on the inner and outer diameters respectively of the piston 781.
- annular chamber 786 is formed between the circumference of the sub 751 and the counterbore 777 and sealed at each end by the O-rings 780, 784 and 785.
- a threaded bore 433 at the back end of the cap 786 receives a hose fitting (not shown) and a small passageway 434 extends inwardly from the threaded bore to communicate the annular chamber 785 with a fluid or air source (not shown) for effecting reciprocation of the piston 782 and fin sleeve 766.
- the operation of the tail fin assembly 750 is best seen with reference to Figs. 31 and 32.
- the piston 782 Under action of compressed air or fluid in the annular chamber 786 the piston 782 begins to move toward the front of the sub 751 and carries the fin sleeve 766 with it.
- the front end of the piston 782 contacts the lugs or splines 761 and the dowel pins 774 become disengaged from the slots 760.
- compressed air or fluid is admitted through the passage 434 from the source into the annular chamber 786.
- the fin sleeve 766 is then free to rotate relative to the tool body.
- the driving force of the tool hammer carries the tool including the sub 751 forward relative to the fin sleeve 766 (Fig. 32).
- the shoulder 771 moves the piston rearwardly and the dowel pins 774 become engaged once again in the slots or splines 760 and the fin sleeve 766 becomes locked against rotational movement relative to the tool body.
- the cycle may be selectively repeated as necessary for proper alignment of the slanted nose member and attitude adjustment of the tool.
- Figs. 33 and 34 are partial longitudinal cross sections of another variation of the fixed/lockable fin assembly using a series of dowel pins and drive teeth to prevent rotational movement.
- the tail fin assembly 800 comprises a cylindrical connecting sub 801 having external threads 802 at the front end which are received within the internal threads at the rear portion of the tool body.
- the circumference of the sub 801 has a first reduced diameter portion 803, and a second reduced diameter 804 forms a shoulder 805 therebetween.
- a third reduced diameter 806 forms a third shoulder 807.
- the third diameter 806 extends longitudinally from the shoulder 807 and is provided with exterior threads 808 at the back end.
- a thin cylindrical retainer ring 809 is received on the first reduced diameter 803 of the sub 801 by screws 810.
- the rear end of the ring 809 extends a short distance beyond the shoulder 805 to surround the forward end of the reduced diameter 804.
- a rod wiper 811 is contained on the interior of the rear end of the ring 809.
- An elongated hollow cylindrical rotating fin sleeve 812 has a central longitudinal bore 813, and a rear counterbore 814 of larger diameter extending inwardly from the back end and defining an annular shoulder 815 therebetween.
- An annular bushing 816 is provided on the central bore and an other bushing 817 is provided on the counterbore 814.
- the outer circumference of the fin sleeve 812 is provided with front reduced diameter 818 and a rear reduced diameter 819.
- the fin sleeve 812 is slidably and rotatably received on the sub 801 with the central bore 813 on the second reduced diameter 804 and the front reduced diameter 818 within the extended portion of the ring 809.
- a series of drive teeth 428 previously shown and described with reference to Fig. 22 are formed on the back end of the fin sleeve 812.
- a plurality of radially and angularly opposed fins 820 are secured to the exterior of the rotating fin sleeve 812 to extend radially outward therefrom.
- the fins 820 are secured at opposing angles relative to the longitudinal axis of the sleeve 812 to impart a rotational force on the sleeve.
- An elongated hollow cylindrical cap 821 having a central bore 822 provided with interior threads 823 and a counterbore 824 extending inwardly from the front end and defining a shoulder 825 therebetween is received on the threads 808 of the sub and within the counterbore 814 of the fin sleeve 812.
- An annular 0-ring 826 on the bore 822 provides a seal on the third reduced diameter 806 of the sub 801, and another O-ring 827 on the counterbore 814 provides a seal on the reduced portion of a piston member described hereinafter.
- a plurality of circumferentially spaced dowel pins 828 extend radially outward through the side wall of the fin sleeve 812 (shown out of position).
- a cylindrical reciprocating piston 829 is slidably received on the third reduced diameter 806 of the sub 801.
- the rear portion 830 of the piston 829 is smaller in diameter than the outer circumference defining a shoulder 831 therebetween.
- the outer circumference of the piston 829 is received in the annulus between the third reduced diameter 806 and the fin sleeve counterbore 814 and the rear portion 830 is received in the annulus between the third reduced diameter 806 and counterbore 824 of the cap 821.
- An annular 0-ring 832 is provided on the inner diameter of the piston 829. With the piston 829 properly positioned, an annular chamber 833 is formed between the back end of the piston and the counterbore 824 of the cap 821 and sealed by the O-rings 826, 827, and 832.
- a threaded bore 433 at the back end of the cap 821 receives a hose fitting (not shown) and a small passageway 434 extends inwardly from the threaded bore to communicate the annular chamber 833 with a fluid or air source (not shown) for effecting reciprocation of the piston 829 and fin sleeve 812.
- a second thin cylindrical retainer ring 834 is secured on the rear reduced diameter 819 of the fin sleeve 812 by screws 835 and extends rearwardly to surround the drive teeth 428 and the dowel pins 828.
- the rear end of the ring 834 extends a distance beyond the dowel pins 828 and is provided with a rod wiper 836.
- the operation of the tail fin assembly 800 is best seen with reference to Figs. 33 and 34.
- the piston 829 Under action of compressed air or fluid in the annular chamber 833 the piston 829 begins to move toward the front of the sub 801 contacting the shoulder 815 and carrying the fin sleeve 812 with it.
- the front end of the piston 829 contacts the shoulder 815 and the drive teeth ecome disengaged from the dowel pins 828.
- compressed air or fluid is admitted through the passage 434 from the source into the annular chamber 833.
- the fin sleeve 812 is then free to rotate relative to the tool body.
- the driving force of the tool hammer carries the tool including the sub 801 forward relative to the fin sleeve 812 (Fig. 34).
- the shoulder 815 moves the piston rearwardly and the drive teeth 428 become engaged once again with the dowel pins 828 and the fin sleeve 812 becomes locked against rotational movement relative to the tool body.
- the cycle may be selectively repeated as necessary for proper alignment of the slanted nose member and attitude adjustment of the tool.
- Fig. 35 is a longitudinal cross sectional view of a movable tail fin assembly.
- Fig. 36 is a vertical cross sectional view of the movable tail fin assembly of Fig. 35 taken along line 36 -36 of Fig. 35.
- the movable tail fin arrangement is similar to the fixed/lockable tail fins previously described with the exception that it rotates the boring tool through an inclined, anti-parallel or skewed fin arrangement. When the two fins are parallel, the soil forces acting on their faces prevents rotation of the tool housing and allows the nose member or eccentric hammer to produce a net deflective force which causes the tool to veer in a curved trajectory.
- the movable tail fin assembly 900 comprises a cylindrical connecting sub 901 having external threads at the front end which are received within the internal threads at the rear portion of the tool body.
- the outer rear portion of the sub 901 is reduced in diameter defining a shoulder 902 and provided with external threads 903.
- a series of circumferentialy spaced openings 904 extend radially through the side wall of the sub 901 communicating the interior of the tool to atmosphere.
- a pair of opposed J-slots 905 extend longitudinally inward from the back end of the sub 901 and terminate a distance from the openings 904.
- An annular O-ring seal 906 on the centaI bore 90 provides a seal on the air distribution tube 46.
- a circular opening 908 extends transversly through the rear portion of the sub 901 and the J-slots 905.
- annular arcuate groove 909 is formed in the interior of each circular opening 908 spaced outwardly from each side of the slots 905 and concentric with the opening 908, and a small opening 910 extends from each groove to the outer surface of the sub 901. The openings are used to fill the grooves with ball bearings 911 after which they are enclosed by threaded plugs 912
- a piston spool 913 is slidably received on the air distribution tube 46.
- the piston spool 913 comprises an elongated cylindrical member having a central longitudinal bore 914 with an 0-nng seal 915 near the back end to seal on the tube 46.
- the front portion of the spool 913 is in the form of a tubular extension 916 and has a short reduced diameter 917 at the forward end.
- the rear portion of the spool has an enlarged diameter 918 greater than the extension 916 to define a shoulder 919 therebetween.
- An O-ring seal 920 is provided on the enlarged diameter 918.
- a pair of radially opposed threaded bores 921 and 922 extend longitudinally through the rear portion of the spool 913 to receive hose fittings for connection to an air or fluid source (not shown).
- a cylindrical piston 923 having a central bore 924 is slidably mounted on the circumference of the tubular extension 916.
- a pair of radtWLly opposed bores 925 and 926 in axial alignment with the bores 921 and 922 extend longitudinally through the piston 923 and are provided with internal threads 927 at the rear portion.
- An O-ring seal 928 disposed in the central bore 924 provides a reciprocating seal on the tubular extention 916.
- Another O-ring seal 929 is provided on the circumference of the piston 923.
- a cylindrical bulkhead 930 having a central bore 931 is mounted on the forward end of the tubular extension 916.
- a pair of radially opposed bores 932 and 933 in axial alignment with the bores 925 and 926 extend longitudinally through the bulkhead 930 and are provided with internal 0- ring seals 934.
- An 0-ring seal 935 disposed in the central bore 931 provides a seal on tubular extension 916.
- Another O-ring seal 936 is provided on the circumference of the bulkhead 930.
- a slot 937 extends vertically through one side wall of the bulk head at the forward end and receives a rectangular key 938 for keying the bulkhead to the back end of sub 901.
- An actuating rod 939 having a flat rectangular front portion 940 and a longitudinally offset round tail portion 941 is carried by the piston 923.
- the front portion of the actuating rod 939 is slidably recived in the elongated portion of the J-slot 905 and the tail portion 941 extends outwardly therefrom to be slidably received through the bulkhead bore 932 and provided with external threads at the rear end which are received on the threads 927 of the bore 925 in the piston 923.
- the rectangular front portion 940 is provided with a transverse slot 942 which engages the protruding lug of a cup- shaped member. described hereinafter.
- An O-ring seal 948 is disposed on the circumference of the tail portion 941 to provide a seal on the piston bore 925.
- a longer, reverse actuating rod 943 having a flat rectangular front portion 944 and a longitudinally offset round tail portion 943 is carried by the piston 923.
- the front portion of the actuating rod 943 is slidably recived in the elongated portion of the opposing J-slot 905 and the tail portion 945 extends outwardly therefrom to be slidably received through the opposed bulkhead bore 933 and provided with external threads which are received on the threads 927 of the bore 926 in the piston 923.
- a reduced diameter 946 extends rearwardly from the threads 927 and is slidably received within the bore 922 of the piston spool 913.
- the rectangular front portion 944 is provided with a transverse slot 947 which engages the protruding lug of another cupshaped member (hereinafter described).
- An O-ring seal 948 is disposed on the circumference of the tail portion 945 to provide a seal on the piston bore 926.
- An elongated hollow cylindrical outer sleeve 949 is slidably received on the outer periphery of the bulkhead 930, the piston 923, and the piston sleeve 913.
- the outer sleeve 949 has interior threads 950 at the front portion, a central longitudinal bore 951 extending therefrom and terminating at a reduced bore 952 defining an annular shoulder 953 therebetween.
- the outer sleeve 949 is threadedly received on the threaded portion of the sub 901 with a seal 954 provided between the front end and the sub shoulder 902.
- a pair of circular openings 955 extend transversly through the side wall of the sleeve in axial alignment with the opening 908 to receive the cup-shaped members - (described hereinafter).
- the reduced bore 952 is received on a short reduced diameter 956 of the piston spool 913 and the O-rings 920, 929, and 936 providing a seal on the central bore 951.
- the side wall of the sleeve forms a sealed front chamber 957 between the bulkhead 930 and the piston 923.
- a second rear chamber 958 is formed between the piston 923 and the piston sleeve 913.
- a small passageway 959 extends inwardly from the back end of the reverse actuating rod 943 and communicates the bore 922 of the piston sleeve 913 with the front chamber 957.
- the opposed bore 921 of the piston sleeve 913 is in communication with the rear chamber 958. It should be understood that the opposed bores 921 and 922 at the back end of the piston sleeve receive hose fittings and flexible hoses extend outwardly therefrom and to be connected to the fluid or air source for effecting reciprocation of the piston.
- a pair of steering fins 960 and 961 each comprising a flat rectangular fin 962 secured to a cylindrical cup-shaped member 963 and 964 are rotatably received within the transverse circular openings 908 and 955.
- Each cup-shaped member is provided with an annular 0-ring seal 965 to provide a rotary seal on the interior of the opening 908, and a circumferential arcuate groove 966 in alignment with the grooves 909 to receive the ball bearings 911.
- the tail fins are locked against outward movement, and are free to rotate about the transverse axis within the openings.
- the opposed cylindrical ends of the cup-shaped members 963 and 964 extend inwardly to meet at the center of the sub 901.
- arcuate eliptical cut-away portion extends transversely across the ends of each cup-shaped member leaving a flat raised segment 967 and a dimetrically opposed protruding lug 968 which is disposed angularly relative to the longitudinal axis of the rectangular fin 962.
- the lugs 968 are diametrically opposed and the elliptical opening surrounds the air distribution tube 46, whether the fins are rotated to a postition parallel or angularly disposed relative to the longitudinal axis of the tool.
- One lug is received in the slot 942 of the actuating rod and the opposing lug is received within the slot 947 of the reverse actuating rod.
- Figs. 35, 37, and 38 The operation of the movable tail fin assembly is best seen with reference to Figs. 35, 37, and 38.
- the piston 923 moves toward the back of the sub 901 carrying the actuating rods 939 and 943 with it.
- This action causes the cup- shaped members 963 and 964 to rotate in opposite directions relative to the transverse axis.
- the air or fluid in the rear chamber 958 has been relieved or exhausted.
- the fins are positioned angularly relative to the longitudinal axis of the tool body.
- the soil forces acting on their faces causes the tool housing to rotate about its longitudinal axis and the toot bores in a straight direction.
- the front chamber 957 is pressurized to move the pistons in the opposite direction (Figs. 37 and 38).
- the fins are positioned parallel to the longitudinal axis of the tool body. In this position, the fins prevent rotation of'the tool housing and the tool bores in a curved direction as a result of the asymmetric boring force of the slanted nose member or the eccentric hammer.
- the positioning of the fins in parallel or anti-parallel positions may be selectively changed as necessary for proper alignment and attitude adjustment of the tool.
- Figs. 40 and 41 are longitudinal cross sections of a portion of a boring tool including an eccentric hammer arrangement.
- An off-axis or eccentric hammer may be used in combination with the tail fin arrangements described previously.
- a deflective side force results. This force causes the boring tool to deviate in the direction opposite to the impact point as depicted in Fig. 40.
- Orientation may be controlled by the external rotation of the tool body with tail fins. The only internal modification required is the replacement of the existing hammer.
- Fig. 40 shows the front portion details of a boring tool 23 which was shown previously in - schematic form in Fig. 8 with a movable tail fin system in combination with an eccentric hammer 24.
- the rear portion of the hammer 24 is not shown, with the understanding that the rear portion of the hammer 24 would be the same as the concentric hammer 37 shown in Fig. 9B.
- the rear portion of the tool is not shown in Figs. 40 or 41 since the eccentric hammer may be used in combination with either the fixed/lockable fin systems or the movable fin systems and with or without the slanted nose member previously shown and described.
- the boring tool 23 comprises an elongated hollow cylindrical outer housing or body 25.
- the outer front end of the body 25 tapers inwardly forming a conical portion 29.
- the internal diameter of the body 23 tapers inwardly near the front end forming a conical surface 30 which terminates in a reduced diameter 31 extending longitudinally inward from the front end.
- the rear end of the body is provided with intemal threads for receiving a tail fin assembly previously described.
- An anvil 33 having a conical back portion 34 and an elongated cylindrical front portion 35 is contained within the front end of the body 23.
- the conical back portion 34 of the anvil 33 forms and interference fit on the conical surface 30 of the body 23, and the elongated cylindrical portion 35 extends outwardly a distance beyond the front end of the body.
- a flat surface 36 at the back end of anvil 33 receives the impact of eccentric reciprocating hammer 24.
- a slanted nose member 18 having a cyUnd,6cal back portion 52 and a central cylindrical bore 53 extending inwardly therefrom may be secured on the cylindrical portion 35 of the anvil 33 (Fig. 40).
- a slot 54 through the sidewall of the cylindrical portion 51 extends longitudinally substantially the length of the central bore 53 and.
- a transverse slot 55 extends radially from the bore 53 to the outer circumference of the cylindrical portion, providing flexibility to the cylindrical portion for clamping the nose member to the anvil.
- Longitudinally spaced holes in alignment with threaded bores 58 on the opposing side of the slot 54 receive screws 59 which secure the nose member 18 to the anvil 33.
- the sidewall of the nose member 18 extends forward from the cylindrical portion 52 and one side is milled to form a flat inclined surface 60.
- the eccentric hammer 24 is an elongated cylindrical member slidably received within the internal diameter 38 of the body 23. A substantial portion of the outer diameter of the hammer 24 is smaller in diameter than the internal diameter 38 of the body, forming an annular cavity 39 therebetween.
- the front portion of the hammer is constructed in a manner to offset the center of gravity of the hammer with respect to its longitudinal axis. As shown in Fig. 40, the side wall of the hammer is provided with a longitudinal slot 970 which places the center of mass eccentric to the iongitudtna! axis and the front surface 43 of the front end of the hammer 24 is shaped to provide an impact centrally on the flat surface 36 of the anvil 33. In Fig.
- the side wall of the hammer 24a is provided with a longitudinal slot 970 and the front surface 43a is radially offset from the longitudinal axis to place the center of mass eccentric to the longitudinal axis and thereby deliver an eccentric impact force on the anvil.
- a series of longitudinal circumferentially spaced slots 972 are provided on the outer surface of the front of the hammer to allow passage of air or fluid from the front end to the reduced diameter portion.
- a key or pin 26 is secured through the side wall of the body 25 to extend radially inward and be received within the slot 970 to maintain the larger mass of the hammer on one side of the longitudinal axis of the tool.
- a relatively shorter portion 40 at the back end of the hammer 37 is of larger diameter to provide a sliding fit against the interior diameter 38 of the body.
- a central cavity 41 extends longitudinally inward a distance from the back end of the hammer 37.
- a cylindrical bushing 42 is slidably disposed within the hammer cavity 41, the circumference of which provides a sliding fit against the inner surface of the central cavity 41.
- Air passages 44 are provided through the sidewall of the hammer 37 inwardly adjacent the shorter rear portion 40 to communicate the central cavity 41 with the annular cavity 39.
- An air distribution tube 45 extends centrally through the bushing 42 and its back end 46 extends outwardly of the body 28 and is connected by fittings 47 to a flexible hose 48.
- the air distribution tube 45 is in permanent communication with a compressed air source (not shown).
- the arrangement of the passages 44 and the bushing 42 is such that, during receiproca- tion of the hammer 37, the air distribution tube 45 alternately communicates via the passages 44, the annular cavity 39 with either the central cavity 41 or atmosphere at regular intervals.
- a cylindrical stop member 49 is secured within the inner diameter of the body 28 near the back end and is provided with a series of longitudinally extending, circumferentially spaced passageways 50 for communicating the interior of the body 28 with atmosphere.
- the air distribution tube 45 is centrally disposed within the stop member 49.
- the hammer 24 moves toward the front of the body 25.
- the hammer imparts an impact on the flat surface 36 of the anvil 33.
- compressed air is admitted through the passages 44 from the central cavity 41 into the annular cavity 39. Since the effective area of the hammer including the larger diameter rear portion 40 is greater than the effective area of the central cavity 41, the hammer starts moving in the opposite direction.
- the bushing 42 closes the passages 44, thereby interruputing the admission of compressed air into annular cavity 41.
- the hammer 37 continues its movement due to the expansion of the the air in the annular cavity 39 until the passages 44 are displaced beyond the ends of the bushing 42, and the annular cavity is placed to communication to atmosphere through the holes 50 in the stop member 49. In this position, the air is exhausted from the annular cavity 39 through the passages 44 now above the trailing edge of the bushing 42 and the holes 50 in the stop member 49. Then the cycle is repeated.
- the eccentric hammer can be used for straight boring by averaging the deflective side force over 360° by rotating the outer body.
- the fins provide orientation capabilities as previously described and are brought into an unlocked rotating or straight parallel alignment position when executing turns. Straight boring of the tool is accomplished by activating the fins to a spin inducing position counteracting the tendency of the eccentric hammer to turn the tool.
- This embodiment consists of an overgage sleeve or sleeves located over a portion of the tool outer surface which are affixed such that they can rotate but cannot slide axially. This permits transmittal of the tool's axial impact force from the tool to the soil while allowing free rotation of the tool during spinning operations.
- the overgage areas are at the front and back of the tool, or alternately, an undergage section in the center of the tool body.
- This undercut in the center of the tool permits a 2- point contact (front and rear) of the tool's outer housing with the soil wall as opposed to the line contact which occurs without the undercut.
- the 2- point contact allows the tool to deviate in an arc without distorting the round cross-sectional profile of the pierced hole.
- a preferred guided horizontal boring tool 1010 having overgage body sections, used with a magnetic field attitude sensing system.
- the boring tool 1010 may be used with various sensing systems, and a magnetic attitude sensing system is depicted generally as one example.
- the usual procedure for using percussion moles is to first locate and prepare the launching and retrieval pits.
- the launching pit P should be dug slightly deeper than the planned boring depth and large enough to provide sufficient movement for the operator.
- the boring tool 1010 is connected to a pneumatic or hydraulic source 11, is then started in the soil, stopped and properly aligned, preferably with a sighting frame and level. The tool is then restarted and boring continued until the tool exists into the retrieval pit (not shown).
- the boring tool 1010 may have a pair of coils 12, shown schematically at the back end, one of which produces a magnetic field parallel to the axis of the tool, and the other produces a magnetic field transverse to the axis of the tool. These coils are intermittently excited by a low frequency generator 13. To sense the attitude of the tool, two coils 14 and 15 are positioned in the pit P, the axes of which are perpendicular to the desired path of the tool. The line perpendicular to the axes of these coils at the coil intersection determines the boresite axis.
- Outputs of these coils can be processed to develop the angle of the tool in both the horizontal and vertical directions with respect to the boresite axis.
- the same set of coils can be utilized to determine the angular rotation of the tool to provide sufficient control for certain types of steering systems. For these systems, the angular rotation of the tool is displayed along with the plane in which the tool is expected to steer upon actuation of the guidance control system.
- the mechanical guidance of the tool can also be controlled at a display panel 16. From controls located at display panel 16, both the operation of the tool 1010 and the pneumatic or hydraulic actuation of the fins 1017 can be accomplished as described hereinafter.
- the boring tool 1010 includes a steering system comprising a slanted-face nose member 1018 attached to the anvil 1033 of the tool to produce a turning force on the tool and tail fins 1017 on a rotary housing 1019a on the trailing end of the tool which are adapted to be selectively positioned relative to the body of the tool to negate the turning force.
- Turning force may also be imparted to the tool by an intemal eccentric hammer, as shown in Fig. 41, above, delivering an off-axis impact to the tool anvil.
- the tail fins 1017 are moved into a position where they may spin about the longitudinal axis of the tool 1010 and the slanted nose member 1018 or eccentric hammer will deflect the tool in a given direction.
- the fins 1017 are moved to a position causing the tool 1010 to rotate about its longitudinal axis, the rotation, will negate the turning effect of the nose member 1018 or eccentric hammer as well as provide a means for orienting the nose piece into any given plane for subsequent turning or direction change.
- the body of the tool 1010 has front 1021 and rear 1022 overgage body sections which give improved performance of the tool in angular or arcuate boring. These overgage sections are fixed longitudinally on the tool body and may be fixed against rotation or may be mounted on bearings which permit them to rotate.
- the steering system of the present invention will allow the operator to avoid damaging other underground services (such as power cables) or to avoid placing underground utilities where they may be damaged.
- the body construction of the tool including the overgage sections cooperates with the steering mechanism to give overall improved performance.
- Figs. 43 through 46 illustrate various embodiments of the boring tool with overgage sections on the tool body.
- a boring tool 1010 having a body 1020 enclosing the percussion mechanism driving the tool.
- the front end of body 1020 is tapered as at 1029 and has the external portion 1035 of the anvil protruding therefrom for percussion boring.
- Front sleeve 1021 and rear sleeve 1022 are mounted on tool body or housing 1020 by a shrink or interference fit
- overgage sleeves 1021 and 1022 are both fixed against longitudinal or rotational slippage.
- the sleeves may be pinned in place as indicated at 1024.
- the rear body portion is connected to a hydraulic or air line for supply of a pressurized operating fluid to the tool.
- boring tool 1010 has a body 1020 enclosing the percussion mechanism driving the tool.
- the front end of body 1020 is tapered as at 1029 and has the external portion 1035 of the anvil protruding therefrom for percussion boring.
- Front sleeve 1021 is mounted on tool body or housing 1020 by a shrink or interference fit.
- the overgage sleeve 1021 is fixed against longitudinal or rotational slippage.
- the sleeve 1021 may be pinned in place as indicated at 1024.
- the rear sleeve 1022 is mounted on body 1020 on bearings 1025 for rotary motion thereon.
- the rear body portion is connected to a hydraulic or air line for supply of a pressurized operating fluid to the tool.
- the protruding anvil portion 1035 was not provided with any special boring surface.
- the tool has a slanted nose member which causes to tool to deviate from a straight boring path at an angle or along an arcuate path.
- the rear of the tool has controllable fins which allow the tool to move without rotation or to rotate about its longitudinal axis. This arrangement is described further below.
- a boring tool 1010 having a body 1020 enclosing the percussion mechanism driving the tool.
- the front end of body 1020 is tapered as at 1029 and has the external portion 1035 of the anvil protruding therefrom for percussion boring.
- the protruding portion 1035 of the anvil has a slanted nose member 1018 secured thereon for angular or arcuate boring.
- Front sleeve 1021 and rear sleeve 1022 are mounted on tool body or housing 1020 by a shrink or interference fit.
- the overgage sleeves 1021 and 1022 are both fixed against longitudinal or rotational slippage.
- the sleeves may be pinned in place as indicated at 1024.
- a rotatable housing 1019a on which there are fins 1017.
- the housing and fin assembly is actuatable between an inactive position in which the tool does not rotate about its axis and an actuated position where the fins cause the tool to rotate.
- the rear body portion is connected to a hydraulic or air line for supply of a pressurized operating fluid to the tool.
- boring tool 1010 has a body 1020 enclosing the percussion mechanism driving the tool.
- the front end of body 1020 is tapered as at 1029 and has the external portion 1035 of the anvil protruding therefrom for percussion boring.
- the protruding portion 1035 of the anvil has a slanted nose member 1018 secured thereon for angular or arcuate boring:
- Front sleeve 1021 is mounted on tool body or housing 1020 by a shrink or interference fit.
- the overgage sleeve 1021 is fixed against longitudinal or rotational slippage.
- the sleeve 1021 may be pinned in place as indicated at 1024.
- the rear sleeve 1022 is mounted on the body 1020 on bearings 1025 for rotary motion thereon.
- a rotatable housing 1019a on which there are fins 1017.
- the housing and fin assembly is actuatable between an inactive position in which the tool does not rotate about its axis and an actuated position where-the fins cause the tool to rotate.
- the rear body portion is connected to a hydraulic or air line for supply of a pressurized operating fluid to the tool.
- Figs. 47A, 47B, and 47C illustrate a boring tool 1027 having a slanted nose member and fixed/lockable fin arrangement as described generally in reference to Figs. 1 and 2 above.
- boring tool 1010 comprises an elongated hollow cylindrical outer housing or body 1028.
- the outer front end of body 1028 tapers inwardly forming a conical portion 1029.
- Sleeve member 1021 is secured on body member 1028 by a shrink or interference fit and is fixed against longitudinal or rotary slippage as previously described.
- the outside diameter of body 1028 tapers inwardly near the front end forming a conical surface 1030 which terminates in a reduced diameter 1031 extending longitudinally inward from the front end.
- the rear end of the body 1028 has internal threads 1032 for receiving a tail fin assembly (see Fig. 47C).
- An anvil 1033 having a conical back portion 1034 and an elongated cylindrical front portion 1035 is positioned in the front end of body 1028.
- the conical back portion 1034 of anvil 1033 forms an interference fit on the conical surface 1030 of the body 1028, and the elongated cylindrical portion 1035 extends outwardly a predetermined distance beyond the front end of the body.
- a flat transverse surface 1036 at the back end of the anvil 1033 receives the impact of a reciprocating hammer 1037.
- Reciprocating hammer 1037 is an elongated cylindrical member slidably received within the cylindrical recess 1038 of the body 1028. A substantial portion of the outer diameter of the hammer 1037 is smaller in diameter than the recess 1038 of the body 1028, forming an annular cavity 1039 therebetween. A relatively shorter portion 1040 at the back end of hammer 1037 is of larger diameter to provide a sliding fit against the interior wall of recess 1038 of body 1028.
- a central cavity 1041 extends longitudinally inward a distance from the back end of the hammer 1037.
- a cylindrical bushing 1042 is slidably disposed within the hammer cavity 1041, the circumference of which provides a sliding fit against the inner surface of the central cavity 1041.
- the front surface 1043 of the front end of the hammer 1037 is shaped to provide an impact centrally on the flat surface 1036 of the anvil 1033.
- the hammer configuration may also be adapted to deliver an eccentric impact force on the anvil.
- An air distribution tube 1045 extends centrally through the bushing 1042 and has a back end 1046 extending outwardly of the body 1028 connected by fittings 1047 to a flexible hose 1048.
- the air distribution tube 1045 is in permanent communication with a compressed air source 11 (Fig. 42).
- the arrangement of the passages 1044 and the bushing 1042 is such that, during reciprocation of the hammer 1037, the air distribution tube 1045 alternately communicates via the passages 1044, the annular cavity 1039 with either the central cavity 1041 or atmosphere at regular intervals.
- a cylindrical stop member 1049 is secured within the recess 1038 in the body 1028 near the back end and has a series of longitudinally-extending, circumferentially-spaced passageways 1050 for exhausting the interior of the body 1028 to atmosphere and a central passage through which the air distribution tube 1045 extends.
- a slanted nose member 1018 has a cylindrically recessed portion 1052 with a central cylindrical bore 1053 therein which is received on the cylindrical portion 1035 of the anvil 1033 (Fig. 47A).
- a slot 1054 through the sidewall of the cylindrical portion 1018 extends longitudinally substantially the length of the central bore 1053 and a transverse slot extends radially from the bore 1053 to the outer circumference of the cylindrical portion, providing flexibility to the cylindrical portion for clamping the nose member to the anvil.
- a flat is provided on one side of cylindrical portion 1018 and longitudinally spaced holes are drilled therethrough in alignment with threaded bores on the other side. Screws 1059 are received in the holes and bores 1058 and tightened to secure nose member 1018 to anvil 1033.
- the sidewall of the nose member 1018 extends forward from the cylindrical portion 1052 and one side is milled to form a flat inclined surface 1060 which tapers to a point at the extended end.
- the length and degree of inclination may vary depending upon the particular application.
- the nose member 1018 may optionally have a flat rectangular fin 1061 (shown in dotted line) secured to the sidewall of the cylindrical portion 1052 to extend substantially the length thereof and radially outward therefrom in a radially opposed position to the inclined surface 1060.
- Slanted nose members 1018 of 2-1/2" and 3-1/2" diameter with angles from 10° to 40° have been tested and show the nose member to be highly effective in turning the tool with a minimum turning radius of 28 feet being achieved with a 3-1/2 inch 15° nose member. Testing also demonstrated that the turning effect of the nose member was highly repeatable with deviations among tests of any nose member seldom varying by more than a few inches in 35 feet of bore. Additionally, the slanted nose members were shown to have no adverse effect on penetration rate and in some cases, actuary increased it.
- the turning radius varies linearly with the angle of inclination. For a given nose angle, the turning radius will decrease in direct proportion to an increase in area.
- the rear sleeve 1022 is mounted on the rear portion of housing 1028 on bearings 1025 for rotary motion thereon.
- the front sleeve 1021 and rear sleeve 1022 provide a 2-point sliding contact on movement of the tool through the hole which is being bored. This provides for reduced friction and facilitates both the linear movement of the tool through the soil and on rotation of the tool by the fins.
- a tail fin assembly 1062 (19a in Fig. 42) is secured in the back end of the body 1028 (Fig. 47C).
- a fixed/lockable tail fin assembly 1062 is illustrated in the example and other variations will be described hereinafter.
- the tail fin assembly 1062 comprises a cyhn- drical connecting sub 1063 having external threads 1064 at the front end which are received within the internal threads 1032 at the back end of the body 1028.
- Sub 1063 has a short reduced outside diameter portion 1065 forming a shoulder 1066 therebetween and a second reduced diameter 1067 adjacent the short portion 1065 forms a second shoulder 1068.
- An 0-ring seal 1069 is located on the reduced diameter 1065 intermediate the shoulders 1066 and 1068.
- the rear portion 1070 of the sub 1063 is smaller in diameter than the second reduced diameter 1067 forming a third shoulder 1071 therebetween and provided with circumferential 0-ring seal 1072 and internal O-ring seal 1073.
- Internal threads 1074 are provided in the rear portion 1070 inwardly of the seal 1073.
- a circumferential bushing 1075 of suitable bearing material such as bronze is provided on the second reduced diameter.
- a series of longitudinal circumferentially spaced grooves or keyways 1076 are formed on the circumference of the rear portion 1070 of the sub 1063.
- a hollow cylindrical piston 1077 is slidably received on the circumference of the rear portion 1070.
- a series of longitudinal circumferentially spaced grooves or keyways 1078 are formed on the interior surface at the front portion of the piston 1077 in opposed relation to the sub keyways 1076.
- a series of keys or dowel pins 1079 are received within the keyways 1076 and 1078 to prevent rotary motion between sub 1063 and piston 1077.
- a first internal cavity 1080 extends inwardly from the keyway 1078 terminating in a short reduced diameter portion 1081 which forms a shoulder 1082 therebetween.
- a second cavity 1083 extends inwardly from the back end 1084 of the piston 1077 terminating at the reduced diameter portion 1081.
- An internal annular O-ring seal 1085 is provided on the reduced diameter portion 1081.
- a series of drive teeth 1086 are formed on the back end of the piston 1077.
- the teeth 1086 comprise a series of circumferentially spaced raised surfaces 1087 having a straight side and an angularly sloping side forming a ratchet.
- a spring 1090 is received within the first cavity 1080 of the piston 1077 and is compressed between the back end 1070 of the sub 1063 and the shoulder 1082 of the piston 1077 to urge the piston outwardly from the sub.
- An elongated, hollow cylindrical rotating fin sleeve 1091 is slidably and rotatably received on the outer periphery of the sub 1063.
- the fin sleeve 1091 has a central longitudinal bore 1092 and a short counterbore 1093 of larger diameter extending inwardly from the front end and defining an annular shoulder 1094 therebetween.
- the counterbore 1093 fits over the short reduced diameter 1065 of the sub 1063 with the 0-ring providing a rotary seal therebetween.
- a flat annular bushing 1095 of suitable bearing material such as bronze is disposed between the shoulders 1068 and 1094 to reduce friction therebetween.
- a hollow cylindrical sleeve 1097 is secured within sleeve 1091 by suitable means such as welding.
- the sleeve 1097 has a central bore 1098 substantially the same diameter as the second cavity 1083 of the piston 1077 and a counterbore 1099 extending inwardly from the back end defining a shoulder 1100 therebetween.
- a series of drive teeth 1101 are formed on the front end of the sleeve 1097.
- the teeth 1101 comprise a series of circumferentially spaced raised surfaces 1102 having a straight side and an angularly sloping side forming a one-way ratchet configuration.
- the teeth correspond in opposed relationship to the teeth 1086 of the piston 1077 for operative engagement therewith.
- a series of flat radially and angularly opposed fins 1105 are secured to the exterior of the fin sleeve 1091 to extend radially outward therefrom. - (Fig. 47C) The fins 1105 are secured at opposing angles relative to the longitudinal axis of the sleeve 1091 to impart a rotational force on the sleeve.
- An elongated hollow cap sleeve 110 having external threads 1107 at the front end is slidably received within the sliding piston 1077 and the sleeve 1097 and threadedly secured in the internal threads 1074 at the rear portion 1070 of the sub 1063.
- the cap sleeve 1106 extends rearwardly from the threads 1107 and an enlarged diameter portion 1108 forms a first shoulder 1109 spaced from the threaded portion and a second enlarged diameter 110 forms a second shoulder 1111 spaced from the first shoulder.
- An O-ring seal 1112 is provided on enlarged diameter 1108 near shoulder 1109 and a second 0-ring seal 1113 is provided on the second enlarged diameter 1110 near the second shoulder 1111.
- the O-ring 1112 forms a reciprocating seal on the interior of the second cavity 1083 of the piston 1077 and the O-ring 113 forms a rotary seal on the counterbore 1099 of the sleeve 1097.
- the 0-ring 1085 in the piston 1077 forms a reciprocating seal on the extended sidewall of the cap 1106.
- An annular chamber 1114 is formed between the exterior of the sidewall of the cap 1106 and the second counterbore 1083 which is sealed at each end by the O-rings 1085 and 112.
- a circumferential bushing 115 is provided on the first enlarged diameter 1108 and an annular bushing 116 on the second enlarged diameter 110 is captured between the shoulders 1100 and 1111 to reduce friction between the sleeve 1097 and the cap 1106.
- the rear portion of the cap 1106 has small bores 1117 arranged to receive a spanner wrench for effecting the threaded connection.
- a threaded bore 1118 at the back end of cap 1106 receives a hose fitting - (not shown) and small passageway 1119 extends inwardly from the threaded bore 1118 to communicate annular chamber 1114 with a fluid or air source (not shown).
- a flexible hose extends outwardly of the cap 1106 and is connected to the fluid or air source for effecting reciprocation of the piston 1077.
- a second small passageway 1120 communicates first cavity 1080 with atmosphere to relieve pressure which might otherwise become trapped therein. Passage 120 may also be used for application of pressure to the forward end of piston 1077 for return movement.
- the tool described above is capable of horizontal guidance, has overgage body sections, and is preferably used with a magnetic field attitude sensing system.
- the boring tool may be used with various sensing systems, and a magnetic attitude sensing system is depicted generally as one example.
- the overgage sleeves may be fixed or rotatable on bearings as described above.
- the overgage sleeves may be used with any percussion boring tool of this general type and is not limited to the particular guidance arrangement, i.e., the slanted nose member and controllable tail fins, described above. It is especially noted that any of the arrangements described in our copending patent application can be used with overgage sleeves to obtain the desired advantages.
- the procedure for using this percussion tool is to first locate and prepare the launching and retrieval pits. As described above, the launching pit P is dug slightly deeper than the planned boring depth and large enough to provide sufficient movement for the operator.
- the boring tool 1010 is connected to a pneumatic or hydraulic source 11, is then started in the soil, stopped and properly aligned, preferably with a sighting frame and level. The tool is then restarted and boring continued until the tool exits into the retrieval pit (not shown).
- the tool can move in a straight direction when used with an eccentric boring force, e.g., the slanted nose member or the eccentric hammer or anvil, provided that the fins are positioned to cause the tool the rotate about its longitudinal axis.
- an eccentric boring force e.g., the slanted nose member or the eccentric hammer or anvil
- the fins are set to allow the tool to move without rotation about the longitudinal axis, the eccentric boring forces cause it to move either at an angle or along an arcuate path.
- the overgage sleeves which are located over a portion of the tool outer surface, are affixed such that they can rotate but cannot slide axially. This permits transmittal of the axial impact force from the tool to the soil while allowing free rotation of the tool during spinning operations.
- the overgage areas are at the front and back of the tool, or alternately, an undergage section in the center of the tool body. This undercut in the center of the tool permits a 2-point contact - (front and rear) of the tool's outer housing with the soil wall as opposed to the line contact which occurs without the undercut.
- the 2-point contact allows the tool to deviate in an arc without distorting the round cross-sectional profile of the pierced hole.
- the tail fins 1017 are moved into a position where they may spin about the longitudinal axis of the tool 1010 and the slanted nose member 1018 or eccentric hammer will deflect the tool in a given direction.
- the fins 1017 are moved to a position causing the tool 1010 to rotate about its longitudinal axis, the rotation will negate the turning effect of the nose member 1018 or eccentric hammer as well as provide the means for orienting the nose piece into any given plane for subsequent turning or direction change.
- the front 1021 and rear 1022 overgage body sections give improved performance of the tool both in straight boring and in angular or arcuate boring. These overgage sections are fixed longitudinally on the tool body and may be fixed against rotation or may be mounted on bearings which permit them to rotate.
- overgage sleeves can be used with any percussion boring tool, they have been shown in combination with one the embodiments described above.
- the operation of this percussion boring tool 1027 is as follows. Under action of compressed air or hydraulic fluid in the central cavity 1041, the hammer 1037 moves toward the front of the body 1028. At the foremost position, the hammer imparts an impact on the flat surface 1036 of the anvil 1033.
- the hammer 1037 continues its movement by the expansion of the air in the annular cavity 1039 until the passages 1044 are displaced beyond the ends of the bushing 1042, and the annular cavity exhausts to atmosphere through the holes 1050 in the stop member 1049. Then the cycle is repeated.
- the operation of the tail fin assembly 1062 is best seen with reference to Fig. 47C.
- the compressed air or fluid in the annular cavity 1114 moves the piston 1077 against the spring 1090 and toward the front of the sub 1063.
- the front end of the piston 1077 contacts the shoulder 1071 and the drive teeth 1086 and 10101 become disengaged.
- compressed air or fluid is admitted through the passage 1119 from the source into the annular chamber 1114.
- the fin sleeve 1091 is then free to rotate relative to the tool body. Pressure which may otherwise become trapped in the first cavity 1080 and hinder reciprocation is exhausted through the pressure relief passage 1120 to atmosphere.
- the passage 1120 may also be connected to a fluid source, i.e. liquid or air, for moving the piston to the rearward position.
- the reciprocal action of the hammer on the anvil and nose member as previosuly described produces an eccentric or asymmetric boring force which causes the tool to move forward through the earth along a path whcih deviates at an angle or along an arcuate path when the tool is not rotating.
- the overgage sleeves support the tool housing at two separ ated points. This 2- point contact (front and rear) of the tool housing with the soil wall allows the tool to deviate in an arc without distorting the round cross-sectional profile of the pierced hole.
- This embodiment relates to the control of the guidance of a percussion boring tool, especially using a magnetic sensing system or sensing tool location and attitude.
- conduits and pipes In the installation of conduits and pipes by various utilities, such as gas, telephone and electric utilities, a problem often faced is the need to install or replace such conduits or pipes under driveways, roads, streets, ditches and/or other structures.
- the utilities use horizontal boring tools to form the bore holes in which to install the conduits or pipes.
- Such tools have been unsatisfactory to the extent that their traverse has not been accurate or controllable. All to frequently other underground utilities have been pierced or the objective target has been missed by a substantial margin. It has aso been difficult to steer around obstacles and get back on course.
- Fig. 48 is illustrated horizontal boring operation in which a borehole 1210 is being bored through the earth 1212 under a roadway 1214 by a horizontal boring tool 1216.
- the particular tool illustrated and for which the preferred embodiment of the present invention was specifically designed is a pneumatic percussion tool, operated like a jack- hammer by a motive mechanism 1217 using compressed air supplied by a compressor 1218 by way of an air tank 1219 over a supply hose 1220.
- the tool 1216 is elongated and has a tool axis 1222 extending in the direction of its length.
- the lead end of the tool 1216 has a piercing point (or edge) 1224 eccentric of he axis 1222.
- the operation of the percussion tool drives the point 1224 through the earth, advancing the tool forward, but slightly off axis.
- the tool 1216 includes a plurality of steering vanes 1226 which may be actuated by pneumatic or hydraulic control energy provided over pneumatic or hydraulic control lines 1228 from a controller 1230 to control the direction and rate rotation of he tool 1216 about its axis. Control signals may also control the operation of the motive mechanism 1217.
- the controller 1230 is supplied with air from the compressor 1218 over a bore 1232.
- the steering vanes 1226 my be turned to cause the tool to rotate at a relatively constant rate.
- the tool then spirals a bit but advances in a substantially straight line in the direction of the axis 1222 because the piercing point 1224 circles the axis and causes the tool to deviate the same amount in each direction, averaging zero. If the vanes 1226 are returned to directions parallel to the axis 1222, the rotation may be stopped with the tool in a desired position, from which it advances asymmetrically in a desired direction.
- the present invention permits an operator to identify the rotational orientation of the tool 1216 about its axis 1222, and hence, to direct the advance of the tool.
- the objective is to bore a hole 1210 relatively horizontally between an input pit 1234 and a target pit 1236 beneath such obstacles as the roadway 1214.
- the hole 1210 must avoid piercing other utility lines 1238 or sewers 1240 or other buried obstacles. These may be identified and located from historical surveyor's drawings or may be located by some other means as by a metal detector or other proximity device 1242.
- the present invention is directed to a control system for sensing the attitude of the tool 1216 and for controlling the steering vanes 1226 to direct the tool along the plotted course.
- the control system includes an electromagnetic source 1244 affixed to the tool 1216 for generating appropriate alternating magnetic flux, a sensing assembly 1246 disposed in one of the pits 1234, 1236, preferably the target pit 1236, and circuitry in the controller 1230 which is powered from a motor-generator set 1248.
- the electromagnetic source 1244 comprises an axial coil 1250 and a transverse coil 1251 rigidly mounted on the tool 1216.
- the coils 1250 and 1251 are alternatively energized from the motor-generator power source 1248 through a controlled power supply section 1252 of the controller 1230 over lines 1253.
- the power source 1248 operates at a relatively low frequency, for example, 1220 Hz.
- the axial coil 1250 generates an axial alternating magnetic field which produces lines of magnetic flux generally symmetrically about the axis 1222 of the tool 1216, as illustrated in Fig. 50.
- the tool 1216 itself is constructed in such manner as to be compatible with the generation of such magnetic field and, indeed , to shape it appropriately.
- the transverse coil 1251 generates a transaxial alternating magnetic field substantially orthogonal to the axis 1222 in fixed relation to the direction of deviation of the point 1224 from the axis 1222 and, hence, indicative of the direction thereof.
- the sensing assembly 1246 is formed of three orthogonal pickup coils 1254, 1256 and 1258, as shown in Figs. 49 and 51, which may be called X, Y and Z coils, respectively. These pickup coils are axially sensitive and can be of the box or solenoidal forms. shown in Figs. 49 and 51.
- the center of the coils may be taken as the origin of a three-dimensional coordinate system of coordinate system of coordinates x, y, z, where x is the general direction of the borehole, y is vertical and z is horizontal.
- the coils 1254, 1256 and 1258 have respective axes extending from the origin of the coordinate ystem in the respective x, y and z directions.
- Figs. 50A, 50B, 50C and 50D are illustrated four possible unique relationships of a sensing coil, the Y coil 1256 as an example, to the lines of flux 60 of the axial magnetic field generated by the axial coil 1250 in the tool 1216.
- Fig. 50A is shown the relationship when the X axis and the tool axis 1222 lie in the same plane with the Y axis of he coil 1256 normal to that plane. That is the relationship when the tool 1216 lies on the plane XZ (the plane perpendicular to the Y axis at the X axis) with the axis 1222 of the tool in that plane.
- Fig. 50A is shown the relationship when the X axis and the tool axis 1222 lie in the same plane with the Y axis of he coil 1256 normal to that plane. That is the relationship when the tool 1216 lies on the plane XZ (the plane perpendicular to the Y axis at the X axis) with the
- FIG. 50B is shown the relationship when the tool 1216 lies in the plane XZ with the tool axis 1222 not in that plane. That is the relationship when the tool 1216 is tilted up or down (up, clockwise, in the example illustrated).
- Fig. 50C is shown the relationship when the tool 1216 is displaced up or down from the plane XZ (up, in the example illustrated) with the tool axis 1222 parallel to the plane XZ.
- Other relationships involve combinations of the relationships shown in Figs. 50B and 50C; that is, where the tool 1216 ties off the XZ plane and has a component of motion transversely thereof.
- Shown in Fig. 50D is the relationship where the combination of displacement (Fig.50C) and tilting (Fig.
- Figs. 50A, 50B, 50C and 50D are for conditions when tool axis 1222 lines in the XY plane - (containing the X and Y axes), but the principle is the same when the tool lies out of such plane.
- the lines of flux linking Y coil 1256 would be different, and the relative signals would be somewhat different. There would, however, still be positions of null similar to those illustrated by Figs. 50A and 50D.
- the pickup coil 1256 will generate no signal under the condition shown in Fig. 50A because no flux links the coil.
- signals will be generated, of phase dependent upon which direction the magnetic field is tilted or displaced from the condition shown in Ftg. 50A.
- the effect of displacement in one direction is exactly offset by tilting so as to generate no signal.
- Fig. 50D if the tool 1216 is off course (off the XZ plane) but the relationship shown in Fig.
- the tool will move toward the sensing assembly 1246 keeping the sensing assembly on a given line of flux 1260. That is, the tool 1216 will home in on the sensing assembly 1246 and get back on course vertically. Similar relationships exist in respect to the Z coil 1258 and horizontal deviation.
- the outputs of the pickup coils 1256, 1258 are applied through a signal conditioner 1262 to a display 1264 in the controller 1230.
- Fig. 50 The relatinships shown in Fig. 50 can also be analyzed geometrically as shown in Fig. 50, where A is the angle between the tool axis 1222 and a line 1265 connecting the center of the tool with the center of the pickup coil 1256, and B is the angle between the line 1265 and the reference axis X, perpendicular to the axis Y of the sensing coil 1256.
- Equation for radial flux density BRand angular flux density B A are: where K, is a constant proportional to the ampere- turns for the axial coil 1250 and inversely proportional to the cube of th distance between the tool 1216 and the sensing coil 1256.
- the singal V thereupon developed in the pickup coil 1256 is proportional to the sum of flux components parallel to the coil axis Y.
- Fig. 51 The circuitry for operating the present invention is shown in greater detail in Fig. 51 in block diagram form.
- the output of the pickup coil 1256 is amplified by an amplifier 1266 and applied to a synchronous detector 1268 to which the output of a regulated power supply 1270 is also applied.
- the regulated power supply 1270 is driven by the same controlled power supply 1252 that drives the coils 1250, 1251 and produces an a.c. voltage of constant amplitude in fixed phase relationship to the voltage applied to the axial coil 1250.
- the synchronous detector 1268 therefore produces a d.c. output of magnitude proportional to the output of the Y coil 1256 and of polarity indicative of phase relative to that of the power supply 1270.
- An amplifier 1272 and a synchronous detector 1274 produce a similar d.c. output corresponding to the output of the Z coil 1258.
- the outputs of the respective synchronous detectors 1268 and 1274 are applied to the display 1264 which displays in y, z coordi-nates the combination of the two signals. This indicates the direction or attitude the tool is off course, permitting the operator to provide control signals over the control lines 1228 to return the tool to its proper course or to modify the course to avoid obstacles, as the case may be.
- the extent to which the tool is off a course leading to the target is indicated by the magnitude of the signals produced in the coils 1256 and 1258.
- the magnitude of the respective signals is also affected by the range of the tool. That is, the farther away the tool, the lesser the flux density and, hence, the lesser the signals generated in the respective pickup coils 1256 and 1258 for a given deviation. It is he function of the X coil 1254 to remove this variable.
- the X coil is sensitive to axial flux density substantially exclusively.
- the y and z directed flux components have negligible effect on its output where the tool 1216 lies within a few degrees of the x direction; e.g., 123.
- the signal from the pickup coil 1254 is amplified by an amplifier 1276 and detected by a synchronous detector 1278 to provide a d. c. output proportional to the flux density strength at the X coil 1254.
- This signal is applied to a control circuit 1280 which provides a field current control for the power supply 1252. This provides feedback to change the power applied to the axial coil 1250 in such direction as to maintain constant the output of the X coil 1254.
- the power from the power supply 1252 is applied to the tool 1216 through a switch 1282.
- the axial coil 1250 When in the switch 1282 position 121, the axial coil 1250 is energized, providing the mode of operation explained above. With the switch 1282 in position 122, the transverse coil 1251 is energized instead. The resulting magnetic field is substantially orthogonal to that provided by the axial coil 1250.
- the signals generated by the Y and Z pickup coils 1256, 1258 then depend primarily upon the relative displacement of the coil 1251 around the axis 1222.
- the displacement of the point is indicated by the relative magnitude of the respective signals from the respective Y and Z coils as detected by the respective synchronous detectors 1268 and 1274 and, hence, is indicated on the display 1264.
- the present invention is useful in a simple form when it is desirable simply to keep the tool on a straight course. This is achieved simply by directing the tool 1216 toward the sensing assembly 1246 while keeping the outputs picked up by the Y and Z coils 1256, 1258 nulled. As mentioned above, it is possible to deviate to avoid obstacles and then return to the course.
- Equation (4) may not be simply approximated.
- the initial tool orientation is determined by means of the sensor coils. Then the tool is allowed to advance an incremental distance, which is also measured. The new location is then determined based on the initial angle and the incremental amount of progress, and integration process. This process is continuously repeated for continuous determination of the position of the tool.
- the sensing assembly 1246 may be moved from place to place or its orientation charged during boring in order to change course.
- the sensor coils can be located on the tool and the source coils can be located on the tool and the source coils placed in either pit
- sensors on the tool 1216 for sensing obstacles hence permit ting control of the direction of tool advance to avoid the obstacles-Other types of boring or drilling systems can be used in conjunction with the present invention, such as hydraulic percussion tools, turbo-drill motors (pneumatic or hydraulic) or rotary-drift type tools.
- the important aspects of the tool are that it include some motive means and a steering mechanism that can be controlled by control signals from afar.
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Abstract
Description
- This invention relates generally to percussion boring tools, and to the steering and control of percussion boring tools.
- Utility Companies often find it necessary to install or replace piping beneath different types of surfaces such as streets, driveways, railroad tracks, etc. To reduce costs and public inconvenience by eliminating unnecessary excavation and restoration, utilities sometimes use underground boring tools to install the new or replacement pipes. Existing boring tools are suitable for boring short distances (up to 60 ft.), but are not sufficiently advanced to provide directional control for longer distances. This lack of control, coupled with the inability of these tools to detect and steer around obstacles, has limited their use to about 20% of all excavations, with the majority of the remaining excavations being performed by open-cut trenching methods.
- Therefore, the development of an economic, guided, horizontal boring tool would be useful to the utility industry, since it would significantly increase the use of boring tools by removing the limitations of poor accuracy and by reducing the occurrence of damage to in-place utilities. Use of such a tool instead of open-cut methods, particularly in developed areas, should result in the savings of millions of dollars annually in repair, landscape restoration and road resurfacing costs.
- Conventional pneumatic and hydraulic percussion moles are designed to pierce and compact compressible soils for the installation of underground utilities without the necessity of digging large launching and retrieval pits, open cutting of pavement or reclamation of large areas of land. An internal striker or hammer reciprocates under the action of compressed air or hydraulic fluid to deliver high energy blows to the inner face of the body. These blows propel the tool through the soil to form an earthen casing within the soil that remains open to allow laying of cable or conduit. From early 1970 to 1972, Bell Laboratories, in Chester, New Jersey, conducted research trying to develop a method of steering and tracking moles. A 4-inch Schramm Pneumagopher was fitted with two steering fins and three mutually orthogonal coils which were used in conjunction with a surface antenna to track the position of the tool. One of these fins was fixed and inclined from the tool's longitudinal axis while the other fin was rotatable.
- Two boring modes could be obtained with this system by changing the position of the rotatable fin relative to the fixed fin. These were (1) a roll mode in which the mole was caused to rotate about its longitudinal center line as it advanced into the soil and (2) a steering mode in which the mole was directed to bore in a curved path.
- The roll mode was used for both straight boring and as a means for selectively positioning the angular orientation of the fins for subsequent changes in the bore path. Rotation of the mole was induced by bringing the rotatable fin into an anti-parallel alignment with the fixed fin. This positioning results in the generation of a force couple which initiates and maintains rotation.
- The steering mode was actuated by locating the rotatable fin parallel to the fixed fin. As the mole penetrates the soil, the outer surfaces of the oncoming fins are brought into contact with the soil and a "slipping wedge" mechanism created. This motion caused the mole to veer in the same direction as the fins point when viewed from the back of the tool.
- Published information on the actual field performance of the prototype appears limited to a presentation by J. T. Sibilia of Bell Laboratories to the Edison Electric Institute in Cleveland, Ohio on October 13, 1972. Sibilia reported that the system was capable of turning the mole at rates of 1 to 1.5° per foot of travel. However, the prototype was never commercialized.
- Several percussion mole steering systems are revealed in the prior art. Coyne et al, U. S. Patent 3,525,405 discloses a steering system which uses a beveled planar anvil that can be continuously rotated or rigidly locked into a given steering orientation through a clutch assembly. Chepur noi et al, U. S. Patent 3,952,813 discloses an off-axis or eccentric hammer steering system in which the striking position of the hammer is controlled by a transmission and motor assembly. Gagen et al, U. S. Patent 3,794,128 discloses a steering system employing one fixed and one rotatable tail fin.
- However, in spite of these and other prior art systems, the practical realization of a technically and cost-effective steering system has been elusive because the prior systems require complex parts and extensive modifications to existing boring tools, or their steering response has been far too slow to avoid obstacles or significantly change the direction of the boring path within the borehole lengths typically used.
- Several steering systems have been developed in an attempt to alleviate this problem by providing control of the boring direction. However, experience indicates that the tool substantially resists sideward movement which seriously limits the steering response. A method is needed by which the tool can travel in a curved path without displacing a significant amount of soil inside the curve. Reducing this resistive side force would provide higher steering rates for the tools. The prior art does not disclose a steerable percussion boring tool having means for reducing friction during boring and turning.
- The tools of the prior art have been unsatisfactory to the extent that their traverse has not been accurate or controllable. All too frequently other underground utilities have been pierced or the objective target has been missed by a substantial margin. It has also been difficult to steer around obstacles and get back on course.
- The directional drilling of holes has probably reached its greatest sophistication in the oil fields. Typical well surveying equipment utilizes magnetometers, inclinometers and inertial guidance systems which are complex and expensive. The wells drilled are substantially vertical.
- In respect to utilities, Bell Telephone Laboratories Incorporated has designed a system for boring horizontal holes wherein the direction of drilling is controlled by deploying a three wire antenna system on the surface of the earth and detecting the position and attitude of the drilling tool in respect thereto by pickup coils on the tool. The signals detected are then used to develop control signals for controlling the steering of the tool. See, for example, MacPherson United States Patent No. 3, 656,161. Such control systems have been relatively expensive, and it is no always easy or convenient to deploy the antenna , for example, over a busy highway.
- Steering control is also known in controlling vehicles, aircraft and missiles. In one form of con- trot a radio beacon is used for guidance, the aircraft simply following a beacon to a runway.
- It is therefore one object of this invention to provide a cost-effective guided horizontal boring tool which can be used to produce small diameter boreholes into which utilities, e.g., electric or telephone lines, TV cable, gas distribution piping, or the like, can be installed.
- It is another object of the present invention to provide a steering system that offers a repeatable and useful steering response in boreholes which is compatible with existing boring equipment and methods and requires only minimal modification of existing boring tools.
- Another object of this invention is to provide a steering system which will enable a horizontal boring tool to travel over great distances and reliably hit a small target
- Another object of this invention is to provide boring tool which will produce a guided borehole to avoid obstacles and to correct for deviations from the planned boring path.
- Another object of this invention is to provide a boring tool immune to adverse environmental conditions and which allows the boring operation to be conducted by typical field service crews.
- A still further object of this invention is to provide a guided horizontal boring tool which requires a minimal amount of excavation for launching and retrieval and thereby reducing the disturbance of trees, shrubs or environmentally sensitive ecosystems.
- Another object of this invention is to provide a horizontal tool having reduced friction during turning and arcuate movement
- Another object of this invention is to provide a boring tool which is constructed to permit transmittal of the impact force of the tool to the soil while permitting free rotation of the tool.
- Another object of this invention is to provide a boring tool with overgage body sections permitting a 2-point contact (front and rear) of the outer housing of the tool with the soil wall as opposed to the line contact which occurs without the undercut.
- Another object of the invention is to provide a percussion boring tool having a body surface configuration permitting the tool to bore in an arc without distorting the round cross-sectional profile of the pierced hole.
- A further object of this invention is to provide a percussion boring tool having a construction in which a higher rate of turning is possible for a given steering force at the front and/or back of the tool since a smaller volume of soil needs to be displaced.
- A still further object of this invention is to pro vide an improved control system for monitoring and controlling the direction of a percussion boring tool.
- Other objects of the invention will become apparent from time to time throughout the specification and claims as hereinafter related.
- A guided horizontal boring tool constructed in accordance with the present invention will benefit utilities and rate payers by significantly reducing installation and maintenance costs of underground utilities by reducing the use of expensive, open-cut trenching methods.
- The above noted objects and other objects of the invention are accomplished by an improved steering system for percussion boring tools. The steering mechanism comprises a slanted-face nose member attached to the anvil of the tool to produce a turning force on the tool and movable tail fins incorporated into the trailing end of the tool which are adapted to be selectively positioned relative to the body of the tool to negate the turning force. Turning force may also be imparted to the tool by an eccentric hammer which delivers an off-axis impact to the tool anvil. The fins also allow the nosepiece to be oriented in any given plane for subsequent turning or direction change.
- The percussion boring tool may optionally have a cylindrical body with overgage sleeves located over a portion of the outer body affixed so that they can rotate but cannot slide axially. The overgage areas at the front and back of the tool, or alternately, an undergage section in the center of the tool body permits a 2-point contact (front and rear) of the outer housing with the soil wall as opposed to the line contact which occurs without the undercut. The 2-point contact allows the tool to deviate in an arc without distorting the round cross-sectional profile of the pierced hole. Thus, for a given steering force at the front and/or back of the tool, a higher rate of turning is possible since a smaller volume of soil needs to be displaced.
- The control system for a percussion boring tool includes a coil disposed on the tool and energized at relatively low frequency to provide a varying magnetic field extending axially from the tool and providing lines of magnetic flux substantially symmetrically disposed about the tool axis. First and second pickup coils are disposed at a distance from the tool. These coils have respective axes at a substantial angle with respect to each other and are mounted to sense the changing flux linked thereby and produce respective first and second electrical signals.
- The coil arrangement provides respective null signals when the respective axes of the pickup coils lie substantially perpendicular to the tool axis and the coils are balanced about the tool axis. The signals therefore indicate the attitude of the tool relative to the coils. A third pickup coil may be used to sense the range of the tool when the third coil has an axis extending generally toward the tool, with its output used to normalize the detection signals. The axes of the three coils are preferably at angles of 90° from each other.
- The signals from the respective pickup coils may be used to determine the attitude of the tool relative to the pickup coils, and the information used to control the steering mechanism of he tool. This may be done automatically. Because this is a null-based system, the control signal may simply operate the steering mechanism to turn the tool the reduce the deviation from null. This causes the system to be a homing device, like a beacon, -and directs the tool along a path to the coils.
- On the other hand, it may be desirable to deviate from a straight path, as to miss obstacles. The system may then direct the tool out of the path, around an obstacle, and back on course.
- Thus, an important aspect of the present invention is to provide a null detection system to determine the attitude of a horizontal boring tool relative to detection coils and for controlling the steering of the tool. Another aspect is to provide a control system for such a tool wherein the tool may be steered to home in on the detection coils.
-
- Fig. 1 is a schematic view and partial vertical section through the earth showing a guided horizontal boring tool illustrating the present invention used with a magnetic attitude sensing system.
- Figs. 2 and 3 are schematic views, in elevation, of a fixed/lockable tail fin steering system.
- Figs. 4 through 7 are schematic views, in elevation, of a movable tail fin system.
- Fig. 8 is a schematic view, in elevation, of a movable fin system in combination with an eccentric hammer.
- Figs. 9A, 9B, and 9C are segments in longitudinal cross section of a typical boring tool having a slanted nose member and fixed/lockable fin arrangement in the unlocked position.
- Fig. 10 is a vertical cross sectional view of the slanted nose member taken along the line 10 -10 of Fig. 9A.
- Fig. 11 is a longitudinal cross section of the fixed/lockable tail fin assembly of Fig. 9C in the locked position.
- Fig. 12 is a view, in side elevation, of the fixed/lockable tail fin assembly of Fig. 9C in the locked position.
- Fig. 13 is a partial elevation of the drive teeth assembly of the fixed/lockable tail fin assembly.
- Figs. 14 and 15 are schematic views in longitudinal cross section showing the operation of a typical percussion boring tool according to this invention.
- Figs. 16 through 19 are partial longitudinal cross sections of a variations of the fixed/lockable fin assembly in the locked or unlocked positions.
- 'Figs. 20 and 21 are longitudinal cross sections of an alternate embodiment of the fixed/lockable fin assembly using a drive pin arrangement
- Fig. 22 is a partial elevation of the dowel pin and drive teeth of the fixed/lockable tail fin assembly.
- Figs. 23, 24, 27, 28, 33 and 34 are partial longitudinal cross sections of variations of the fixed/lockable fin assembly using a dowel pin and drive teeth drive, while Figs. 25 and 26 illustrate a splined connection, and
- Figs. 29 -32 show a spline and drive teeth connection..
- Fig. 35 is a longitudinal cross section of a movable tail fin assembly.
- Fig. 36 is a vertical cross section of the movable tail fin assembly of Fig. 35 taken along line 36 -36 of Fig. 35.
- Figs. 37 and 38 are partial longitudinal cross sections of the movable tail fin assembly of Fig. 35 showing the operation.
- Fig. 39 is an end view of the movable tail fin assembly showing the fins in the non-parallel position.
- Figs. 40 and 41 are longitudinal cross sections of a portion of a boring tool including an eccentric hammer arrangement.
- Fig. 42 is a schematic view and partial vertical section through the earth showing a guided horizontal boring tool illustrating an al- temate embodiment of the percussion boring tool with overgage sections on the tool housing and illustrating the tool as used with a magnetic attitude sensing system.
- Fig. 43 is a view, in elevation, of a percussion boring tool having overgage collars, shown in section, secured in fixed positions at the front and rear of the tool housing.
- Fig. 44 is a view, in elevation, of a percussion borring tool having overgage collars, shown in section, one in a fixed position at the front and the other supported on bearings for rotation at the rear of the tool housing.
- Fig. 45 is a view, in elevation, of a percussion boring tool having overgage collars, shown in section, secured in fixed positions at the front and rear of the tool housing and further showing a slant nosed boring member at the front and spin controlling fins at the rear.
- Fig. 46 is a view, in elevation, of a percussion boring tool having overgage collars, shown in section, one in a fixed position at the front and the other supported on bearings for rotation at the rear of the tool housing and further showing a slant nosed boring member at the front and spin controlling fins at the rear.
- Figs. 47A, 47B, and 47C are segments in longitudinal cross section of a boring tool as shown in Fig. 5 having a slanted nose member and fixed/lockable fin arrangement in the unlocked position.
- Fig. 48 is a vertical sectional view, partly diagrammatic and partly in perspective, of a horizontal boring operation, showing a horizontal boring tool controlled by a control system according to the present invention;
- Fig. 49 is a diagrammatic illustration of the sensing system of he control system of the present invention;
- Fig. 50A, 50B, 50C and 50D are diagrammatic illustrations of relationships of one sensing coil and the magnetic flux generated by the flux generator of the sensing system shown in Fig. 49; and
- Fig. 51 is a diagrammatic illustration of the electrical circuitry of the sensing system shown in Fig. 49.
- Referring to the drawings by numerals of reference, and particularly to Fig. 1, there is shown a preferred guided horizontal
boring tool 10 used with a magnetic field attitude sensing system. Theboring tool 10 may be used with various sensing systems, and a magnetic attitude sensing system is depicted generally as one example. The usual procedure for using percussion moles is to first locate and prepare the launching and retrieval pits. The launching pit P should be dug slightly deeper than the planned boring depth and large enough to provide sufficient movement for the operator. The mole orboring tool 10 is connected to a pneumatic orhydraulic source 11, is then started in the soil, stopped and properly aligned, preferably with a sighting frame and level. The tool is then restarted and boring continued until the tool exits into the retrieval pit (not shown). - The
boring tool 10 may have a pair ofcoils 12 at the back end, one of which produces a magnetic field parallel to the axis of the tool, and the other produces a magnetic field transverse to the axis of the tool. These coils are intermittently excited by alow frequency generator 13. To sense the attitude of the tool, twocoils - Outputs of these coils can be processed to develop the angle of the tool in both the horizontal and vertical directions with respect to the boresite axis. Using the transverse field, the same set of coils can be utilized to determine the angular rotation of the tool to provide suffi+cient control for certain types of steering systems. For these systems, the angular rotation of the tool is displayed along with the plane in which the tool is expected to steer upon actuation of the guidance control system.
- The mechanical guidance of the tool can also be controlled at a
display panel 16. From controls located atdisplay panel 16, both the operation of thetool 10 and the pneumatic or hydraulic actuation of thefins 17 can be accomplished as described hereinafter. - As shown in Fig. 1, the
boring tool 10 includes a steering system with a slanted-face nose member 18 attached to theanvil 33 of the tool to produce a turning force on the tool andtail fins 17 on arotary housing 19 on the trailing end of the tool adapted to be selectively positioned relative to the body of the tool to negate the turning force. Turning force may also be imparted to the tool by an internal eccentric hammer (Fig. 41) described hereinafter which delivers an off-axis impact to the tool anvil. - For turning the tool, the
tail fins 17 are moved into a position where they may spin about the longitudinal axis of thetool 10 and theslanted nose member 18 or eccentric hammer will deflect the tool in a given direction. When thefins 17 are moved to a position causing thetool 10 to rotate about its longitudinal axis, the rotation will negate the turning effect of thenose member 18 or eccentric hammer as well as provide a means for orienting the nose piece into any given plane for subsequent turning or direction change. It should be understood that either an eccentric hammer or anvil will produce the desired turning force, since the only requirement is that the axis of the impact does not pass through the frontal center of pressure. - The steering system of the present invention will allow the operator to avoid damaging other underground serv ices (such as power cables) or to avoid placing underground utilities where they may be damaged.
- Figs. 2 through 7 illustrate various combinations and implementations of the combination slanted nose member and tail fins steering system - schematically and illustrates the basic operation of each design. The function of the tail fins is to provide a method of executing controlled changes to the boring direction.
- A fixed/lockable tail
fin steering system 17 is illustrated in Figs. 2 and 3. To turn thetool 10, the tool is allowed to rotate about the longitudinal axis due to the turning force of the tail fins when in the locked position until the proper tool face orientation is obtained (Fig. 2). Thehousing 19 is then unlocked and spins freely, whereby the tool moves in a curved path by the turning force of the slantedface nose member 18. Straight boring by thetool 10 is accomplished by lockingtail fin housing 19 to themain body 20 of the tool 10 (Fig. 3), to rotate the tool body and thus negate the turning action of the slantednose member 18. - A
boring tool 21 having a movable tail fin system is illustrated in Figs. 4 -7. To turn or change direction of thetool 21, thetail fins 22 are activated to a parallel position relative to the longitudinal axis of thetool body 20 and thetool 21 is allowed to turn relative to the longitudinal axis due to the turning force of thenose member 18 or the eccentric hammer. Proper tool face orientation is obtained (Figs. 4 and 5) by use of the tail fins in a skewed inclined position. Straight boring of the tool is accomplished by activating thefins 22 to an inclined position relative to the mole axis (Figs. 6 and 7) to rotate the tool body and thus negate the turning action of the slantednose member 18. - Fig. 8 illustrates a
boring tool 23 with a movable tail fin system in combination with aneccentric hammer 24. It should be understood that the eccentric hammer may be used in combination with either the fixed/lockable fin system or the movable fin system and with or without the slanted nose member, depending upon the particular application. Either an eccentric hammer or anvil will produce the desired result, since the only requirement is that the axis of the impact does not pass through the frontal center of pressure. Unless negated by one of the previously described fin systems, theeccentric hammer 24 provides the side force required to turn the tool. - The
eccentric hammer 24 is keyed to themain body 25 of thetool 23 by apin 26 or other suitable menas to maintain the larger mass of the hammer on one side of the longitudinal axis of the tool. Turning of thetool 23 is accomplished by unlocking the tail fin housing of the fixedflockable embodiment from the main mole body or turning the fins of the movable fin embodiment to a position parallel to the body axis. The parallel fins or unlocked housing position eliminates the fins ability to negate the eccentric hammer force. To steer thetool 23, the tail fin housing is unlocked or the fins are activated to a skewed inclined position relative to the tool body axis and the tool is turned by the eccentric hammer force until the proper tool face orientation is obtained. - Straight boring is accomplished in all of the previously described implementations by continuously rotating the tool. This distributes the turning force over 360° and causes the tool to bore a helical (nearly straight) hole.
- Figs. 9A, 9B, 9C, and 10 illustrate a typical
boring tool 27 having a slanted nose member and fixedllockable fin arrangement as described generally in reference to Figs. 1 and 2. As shown, theboring tool 10 comprises an elongated hollow cylindrical outer housing orbody 28. The outer front end of thebody 28 tapers inwardly forming aconical portion 29. The internal diameter of thebody 28 tapers inwardly near the front end forming aconical surface 30 which terminates in a reduceddiameter 31 extending longitudinally inward from the front end. The rear end of thebody 28 hasinternal threads 32 for receiving a tail fin assembly (see Fig. 9C). - An
anvil 33 having aconical back portion 34 and an elongated cylindricalfront portion 35 is positioned in the front end ofbody 28. Theconical back portion 34 ofanvil 33 forms an interference fit on theconical surface 30 of thebody 28, and the elongatedcylindrical portion 35 extends outwardly a predetermined distance beyond the front end of the body. A flattransverse surface 36 at the back end ofanvil 33 receives the impact of areciprocating hammer 37. - Reciprocating
hammer 37 is an elongated cylindrical member slidably received within thecylindrical recess 38 of thebody 28. A substantial portion of the outer diameter of thehammer 28 is smaller in diameter than therecess 38 of thebody 28, forming anannular cavity 39 therebetween. A relativelyshorter portion 40 at the back end of thehammer 37 is of larger diameter to provide a sliding fit against the interior wall ofrecess 38 of thebody 28. - A
central cavity 41 extends longitudinally inward a distance from the back end of thehammer 37. Acylindrical bushing 42 is slidably disposed within thehammer cavity 41, the circumference of which provides a sliding fit against the inner surface of thecentral cavity 41. Thefront surface 43 of the front end of thehammer 37 is shaped to provide an impact centrally on theflat surface 36 of theanvil 33. As described hereinafter, the hammer configuration may also be adapted to deliver an eccentric impact force on the anvil. -
Air passages 44 in the sidewall ofhammer 37 inwardly adjacent the shorterrear portion 40 communicate thecentral cavity 41 with theannular cavity 39. Anair distribution tube 45 extends centrally through thebushing 42 and has aback end 46 extending outwardly of thebody 28 connected byfittings 47 to a flexible hose 48. For reciprocating thehammer 37, theair distribution tube 45 is in permanent communication with a compressed air source 11 (Fig. 1). The arrangement of thepassages 44 and thebushing 42 is such that, during reciprocation of thehammer 37, theair distribution tube 45 alternately communicates via thepassages 44, theannular cavity 39 with either thecentral cavity 41 or atmosphere at regular intervals. - A
cylindrical stop member 49 is secured within therecess 38 in thebody 28 near the back end and has a series of longitudinally-extending, circumferentially-spacedpassageways 50 for exhausting the interior of thebody 28 to atmosphere and a central passage through which theair distribution tube 45 extends. - A slant-
end nose member 18 has a cylindrically recessedportion 52 with a central cylindrical bore 53 therein which is received on thecylindrical portion 35 of the anvil 33 (Figs. 9A and 10). Aslot 54 through the sidewall of thecylindrical portion 18 extends longitudinally substantially the length of thecentral bore 53 and a transverse slot extends radially from thebore 53 to the outer circumference of the cylindrical portion, providing flexibility to the cylindrical portion for clamping the nose member to the anvil. A flat 56 is provided on one side ofcylindrical portion 18 and longitudinally spaced holes 57 are drilled therethrough in alignment with threadedbores 58 on the other side.Screws 59 are received in the holes 57 and bores 58 and tightened to secure thenose member 18 to theanvil 33. - The sidewall of the
nose member 18 extends forward from thecylindrical portion 52 and one side is milled to form a flatinclined surface 60 which tapers to a point at the extended end. The length and degree of inclination may vary depending upon the particular application. Thenose member 18 may optionally have a flat rectangular fin 61 (shown in dotted line) secured to the sidewall of thecylindrical portion 52 to extend substantially the length thereof and radially outward therefrom in a radially opposed position to theinclined surface 60. -
Slanted nose members 18 of 2-1/2" and 3-1/2" diameter with angles from 10° to 40° (as indicated by angle "A") have been tested and show the nose member to be highly effective in turning the tool with a minimum turning radius of 28 feet being achieved with a 3-1/2inch 15 degree nose member. Testing also demonstrated that the turning effect of the nose member was highly repeatable with deviations among tests of any nose member seldom varying by more than a few inches in 35 feet of bore. Additionally, the slanted nose members were shown to have no adverse effect on penetration rate and in some cases actually increased it. - It has also been found that the turning radius varies linearly with the angle of inclination. For a given nose angle, the turning radius will decrease in direct proportion to an increase in area.
- A
tail fin assembly 19 is secured in the back end of the body 28 (Fig. 9C). A fixed/lockabletail fin assembly 19 is illustrated in the example and other variations will be described hereinafter. Thetail fin assembly 19 comprises acylindrical connecting sub 63 havingexternal threads 64 at the front end which are received within theinternal threads 32 at the back end of thebody 28.Sub 63 has a short reduced outside diameter portion 65 formingshoulder 66 therebetween and a second reduced diameter 67 adjacent the short portion 65 forms asecond shoulder 68. - An O-
ring seal 69 is located on the reduced diameter 65 intermediate theshoulders rear portion 70 of thesub 63 is smaller in diameter than the second reduced diameter 67 forming athird shoulder 71 therebetween and provided with a circumferential 0-ring seal 72 and an internal 0-ring seal 73.Internal threads 74 are provided in therear portion 70 inwardly of theseal 73. Acircumferential bushing 75 of suitable bearing material such as bronze is provided on the second reduced diameter 67. - A series of longitudinal circumferentially spaced grooves or
keyways 76 are formed on the circumference of therear portion 70 of thesub 63. Ahollow cylindrical piston 77 is slidably received on the circumference of therear por tion 70. A series of longitudinal circumferentially spaced grooves orkeyways 78 are. formed on the interior surface at the front portion of thepiston 77 in opposed relation to thesub keyways 76. A series of keys or dowel pins 79 are received within thekeyways sub 63 and thepiston 77. - A first
internal cavity 80 extends inwardly from thekeyway 78 terminating in a short reduced diameter portion 81 which forms a shoulder 82 therebetween. Asecond cavity 83 extends inwardly from the back end 84 of thepiston 77 terminating at the reduced diameter portion 81. An internal annular 0-ring seal 85 is provided on the reduced diameter portion 81. As shown in Figs. 9C and 13, a series ofdrive teeth 86 are formed on the back end of thepiston 77. Theteeth 86 comprise a series of circumferentially spaced raisedsurfaces 87 having astraight side 88 and anangularly sloping side 89 forming a one-way ratchet configuration. Acompression spring 90 is received within thefirst cavity 80 of thepiston 77 and is compressed between theback end 70 of thesub 63 and the shoulder 82 of thepiston 77 to urge the piston outwardly from the sub. - An elongated, hollow cylindrical
rotating fin sleeve 91 is slidably and rotatably received on the outer periphery ofsub 63. Thefin sleeve 91 has a centrallongitudinal bore 92 and a short counterbore 93 of larger diameter extending inwardly from the front end and defining anannular shoulder 94 therebetween. The counterbore 93 fits over the short reduced diameter 65 of thesub 63 with the O-ring 69 providing a rotary seal therebetween. A flatannular bushing 95 of suitable bearing material such as bronze is disposed between theshoulders fin sleeve 91. - A hollow
cylindrical sleeve 97 is secured within the second counterbore by suitable means such as welding. Thesleeve 97 has acentral bore 98 substantially the same diameter as thesecond cavity 83 of thepiston 77 and acounterbore 99 extending inwardly from the back end defining shoulder 100 therebetween. As shown in Figs. 9C and 13, a series ofdrive teeth 101 are formed on the front end of thesleeve 97. Theteeth 101 comprise a series of circumferentially spaced raisedsurfaces 102 having astraight side 103 and an angularlysloping side 104 forming a one-way ratchet configuration. The teeth correspond in opposed relationship to theteeth 86 of thepiston 77 for operative engagement therewith. - A series of flat radially and angularly opposed
fins 105 are secured to the exterior of thefin sleeve 91 to extend radially outward therefrom. - (Figs. 9C, 11 and 12) Thefins 105 are secured at opposing angles relative to the longitudinal axis of thesleeve 91 to impart a rotational force on the sleeve. - An elongated
hollow cap sleeve 106 havingexternal threads 107 at the front end is slidably received within the slidingpiston 77 and thesleeve 97 and threadedly secured in theinternal threads 74 at therear portion 70 of thesub 63. Thecap sleeve 106 extends rearwardly from thethreads 107 and anenlarged diameter portion 108 forms a first shoulder 109 spaced from the threaded portion and a secondenlarged diameter 110 forms asecond shoulder 111 spaced from the first shoulder. - An O-
ring seal 112 is provided on theenlarged diameter 108 near the shoulder 109 and a second O-ring seal 113 is provided on the secondenlarged diameter 110 near thesecond shoulder 111. The O-ring 112 forms a reciprocating seal on the interior of thesecond cavity 83 of thepiston 77 and the O-ring 113 forms a rotary seal on thecounterbore 99 of thesleeve 97. The 0-ring 85 in thepiston 77 forms a reciprocating seal on the extended sidewall of thecap 106. - An
annular chamber 114 is formed between the exterior of the sidewall of thecap 106 and thesecond counterbore 83 which is sealed at each end by the 0-rings circumferential bushing 115 is provided on the firstenlarged diameter 108 and anannular bushing 116 on the secondenlarged diameter 110 is captured between theshoulders sleeve 97 and thecap 106. The rear portion of thecap 106 hassmall bores 117 arranged to receive a spanner wrench for effecting the threaded connect ion. A threadedbore 118 at the back end of thecap 106 receives a hose fitting (not shown) and asmall passageway 119 extends inwardly from the threaded bore 118 to communicate theannular chamber 114 with a fluid or air source (not shown). A flexible hose extends outwardly of thecap 106 and is connected to the fluid or air source for effecting reciprocation of thepiston 77. A secondsmall passageway 120 communicates thefirst cavity 80 with atmosphere to relieve pressure which might otherwise become trapped therein.Passage 120 may also be used for application of pressure to the forward end of thepiston 77 for return movement - Having thus described the major components of the boring toot assembly, an explanation of the operation of a typical boring tool and the tail fin assembly follows.
- The operation of the percussion boring roo¡ 27 is illustrated schematically in Figs. 14 and 15. Under action of compressed air or hydraulic fluid in the
central cavity 41, thehammer 37 moves toward the front of thebody 28. At the foremost position, the hammer imparts an impact on theflat surface 36 of theanvil 33. - In this position (Fig. 14), compressed air is admitted through the
passages 44 from thecentral cavity 41 into theannular cavity 39. Since the effective area of the hammer including the larger diameterrear portion 40 is greater than the effective area of thecentral cavity 41, the hammer starts moving in the opposite direction. During this movement, thebushing 42 closes the passages 44 (Fig. 15), thereby interrupting the admission of compressed air intoannular cavity 41. - The
hammer 37 continues its movement by the expansion of the the air in theannular cavity 39 until thepassages 44 are displaced beyond the ends of thebushing 42, and the annular cavity exhausts to atmosphere through theholes 50 in thestop member 49. In this position, the air is exhausted from theannular cavity 39 through thepassages 44 now above the trailing edge of thebushing 42 and theholes 50 in thestop member 49. Then the cycle is repeated. - The operation of the
tail fin assembly 62 is best seen with reference to Figs. 9C and 11. The compressed air or fluid in theannular cavity 114 moves thepiston 77 against the force of thespring 90 and toward the front of thesub 63. In the foremost position, the front end of thepiston 77 contacts theshoulder 71 and thedrive teeth passage 119 from the source into theannular chamber 114. Thefin sleeve 91 is then free to rotate relative to the tool body. - When the air or fluid pressure within the
chamber 114 is relieved, the force of thespring 90 moves thepiston 77 in the opposite direction (Fig. 11). During this movement, thedrive teeth fin sleeve 91 becomes locked against rotational movement relative to the tool body. Pressure which may otherwise become trapped in thefirst cavity 80 and hinder reciprocation is exhausted through thepressure relief passage 120 to atmosphere. The cycle may be selectively repeated as necessary for proper alignment the slantednose member 18 and attitude adjustment of the tool. It should be understood that thepassage 120 may also be connected to a fluid, i.e. liquid or air, source for moving the piston to the rearward position. - Another embodiment of the tail fin assembly clutch mechanism is illustrated in Figs. 16 and 17. Some parts are given the same numerals of reference to avoid repetition. The
tail fin assembly 119 comprises acylindrical connecting sub 163 havingexternal threads 164 at the front end which are received within theinternal threads 32 at the back end of thebody 28.Sub 163 has a short reduced outsidediameter portion 165 forming ashoulder 166. Therear portion 170 of thesub 163 is smaller in diameter than the reduceddiameter 165 forming athird shoulder 171 therebetween and provided with a circumferential 0-ring seal 172. - A series of longitudinal circumferentially-spaced grooves or
keyways 176 are formed on therear portion 170 of thesub 163. A hollowcylindrical piston 177 is slidably received on the circumference of therear portion 170. A series of longitudinal circumferentially spaced grooves orkeyways 178 are formed on the interior surface at the front portion of thepiston 177 in opposed relation to thesub keyways 176. A series of keys or dowel pins 179 are received within thekeyways sub 163 and thepiston 177. - A first
internal cavity 180 extends inwardly from thekeyway 178 terminating in a short reduced diameter portion 181 which forms ashoulder 182 therebetween. Asecond cavity 183 smaller than the first extends inwardly from theback end 184 of thepiston 77 terminating at the reduced diameter portion 181. O-ring seals first cavity 180 and reduced diameter portion 181 respectively. As previously shown and described with reference to Fig. 13, a series ofdrive teeth 86 are formed on the back end of thepiston 177. Theteeth 86 comprise a series of circumferentially spaced raisedsurfaces 87 having astraight side 88 and anangularly sloping side 89 forming a one-way ratchet configuration. - An elongated hollow cylindrical
rotating fin sleeve 191 is rotatably received on the outer periphery of thesub 163. Thefin sleeve 191 has a centrallongitudinal bore 192. Thebore 192 is rotatably received on the reduceddiameter 165 of thesub 163 with the O-ring 169 providing a rotary seal therebetween. A flat annular bushing 195 of suitable material such as bronze is disposed between the shoulder 168 and the front of thefin sleeve 191 to reduce friction. - A hollow
cylindrical sleeve 197 is secured within the rear portion of the fin sleeve bore 192 by suitable means such as welding. Thesleeve 197 has acentral bore 198 substantially the same diameter as thesecond cavity 183 of thepiston 177. As previously shown and described with reference to Fig. 13, a series ofdrive teeth 101 are formed on the front end of thesleeve 197. Theteeth 101 comprise a series of circumferentially spaced raisedsurfaces 102 having astraight side 103 and an angularlysloping side 104 forming a one-way ratchet configuration. The teeth correspond in opposed relationship to theteeth 86 of thepiston 177 for operative engagement therewith. An O-ring 213 and abushing 215 are provided in thecentral bore 198. - A series of flat, radially and angularly opposed
fins 205 are secured to the exterior of thefin sleeve 191 to extend radially outward therefrom. Thefins 205 are secured at opposing angles relative to the longitudinal axis of thesleeve 191 to impart a rotational force on the sleeve. - An elongated hollow
cylindrical cylinder cap 206 havingexternal threads 207 at the front end is slidably received within the slidingpiston 177 and thesleeve 197 and threadedly secured in theinternal threads 174 at therear portion 170 of thesub 163. The circumference of thecap 206 extends rearwardly from thethreads 207 and anenlarged diameter portion 208 formsfirst shoulder 209 spaced from the threaded portion and a secondenlarged diameter 210 formssecond shoulder 211 spaced from the first shoulder. An O-ring seal 212 is provided on theenlarged diameter 208 near theshoulder 209. The O-ring 212 forms a reciprocating seal on the interior of thesecond cavity 183 of thepiston 177 and the O-ring 213 forms a rotary seal on thecentral bore 198 of thesleeve 197. The O-ring 185 in thepiston 177 forms a reciprocating seal on the extended sidewall of thecap 206. - An annular
rear chamber 214 is formed between the exterior of the sidewall of thecap 206 and the secondsmaller bore 183 which is sealed at each end by the 0-rings front chamber 216 is formed between the sidewall of thecap 206, thecavity 180, and the back end of thesub 163, which is sealed by the 0-rings sub 163 hassmall bores 217 arranged to receive a suitable wrench for effecting the threaded connection. A threadedbore 218 at the back end of thecap 206 receives a hose fitting (not shown) and asmall passageway 219 extends inwardly from the threaded bore 218 to communicate therear chamber 214 with a fluid or air source (not shown). Another similar threaded bore at the back end of the cap receives a hose fitting (not shown) and asmall passageway 220 extends inwardly from the threaded bore to communicate thefront chamber 216 with a fluid or air source (not shown). Flexible hoses extend outwardly of thecap 206 and are connected to the fluid or air source for effecting reciprocation of thepiston 177. - The operation of the
tail fin assembly 119 is illustrated schematically in Figs. 16 and 17. Under action of compressed air or fluid in therear chamber 214, thepiston 177 moves toward the front of thesub 163. When in its foremost position, thedrive teeth fin sleeve 191 is free to rotate about the longitudinal axis of the tool body. In this position (Fig. 16), compressed air or fluid in thefront chamber 216 has been exhausted. To lock the tail fins against rotational movement, compressed air or fluid is admitted through thepassage 220 into thefront chamber 216 and exhausted from therear chamber 214 to move thepiston 177 in the opposite direction. In this position (Fig. 17), thedrive teeth - Another variation of the fixedllockable tail fin assembly having drive teeth is illustrated in Figs. 18 and 19. To avoid repetition, some of the components, details, and reference numerals previously shown and described with reference to Figs. 9C and 11 will not be repeated here. Other components previously described will carry the same numerals of reference.
- The
tail fin assembly 219 comprises acylindrical connecting sub 263 having external threads at the front end which are received within the internal threads at the back end of the body. Thesub 263 has a short reduced diameter portion forming a first shoulder. and a second reduced diameter adjacent the short portion forms a second shoulder. An annular O-ring seal is provided on the first reduced diameter intermediate the first and second shoulders. The sidewall of thesub 263 extends rearwardly from the second shoulder. Therear portion 270 of thesub 263 is smaller in diameter than the second reduced diameter forming athird shoulder 268 and a forth reduced diameter defines a fourth shoulder 271. A circumferential O-ring seal 272 is provided at back end of thesub 263.External threads 274 are provided in therear portion 270 inwardly of theseal 272 - A series of circumferentially spaced
spherical apertures 276 are formed on the circumference of the sidewall of thesub 263 near the third shoulder 271 and carry a series ofballs 279. A hollowcylindrical piston 277 is slidably received on the circumference of therear portion 270. A ser ies of longitudinal circumferentially spaced grooves orkeyways 278 are formed on the interior surface at the front portion of thepiston 277 in opposed relation to theballs 279. Theballs 279 withinapertures 276 andkeyways 278 prevent rotary motion betweensub 263 andpiston 277. - A
first cavity 280 extends inwardly from the front end of thepiston 277 and terminates in a short reduceddiameter portion 281 which forms ashoulder 282. Asecond cavity 283 extends inwardly from the back end of thepiston 277 terminating at the reduceddiameter portion 281. An 0-ring seal 285 is provided on the reduceddiameter portion 281. As shown in Fig. 13, a series ofdrive teeth 86 are formed on the back end of thepiston 277. Theteeth 86 comprise a series of circumferentially spaced raisedsurfaces 87 having astraight side 88 and anangularly sloping side 89 forming a one-way ratchet configuration. Acompression spring 290 surrounds the sidewall of thesub 263 and the ends of the spring are biased against theshoulder 268 of thesub 270 and the front end of thepiston 277 to urge the piston outwardly from the sub. - As previously described a hollow cylindrical
rotating fin sleeve 291 having arear counterbore 296 is slidably and rotatably received on the outer periphery ofsub 263. A hollowcylindrical sleeve 297 is secured within thesecond counterbore 296 by suitable means such as welding. Thesleeve 297 has a central bore substantially the same diameter as thesecond cavity 283 of thepiston 277. As shown in Fig. 13, a series ofdrive teeth 101 are formed on the front end of thesleeve 297. Theteeth 101 comprise a series of circumferentially spaced raisedsurfaces 102 having astraight side 103 and an angularlysloping side 104 forming a one-way ratchet configuration. The teeth correspond in opposed relationship to theteeth 86 of thepiston 277 for operative engagement therewith. A series of flat radially and angularly opposed fins as previously described are secured to the exterior of the fin sleeve to extend radially outward therefrom. - An elongated hollow
cylindrical cylinder cap 306 having internal threads 307 at the front end is slidably received within the slidingpiston 277 and thesleeve 297 and threadedly secured on theexternal threads 274 at therear portion 270 of thesub 263. An 0-ring seal 312 is provided on the outer front portion ofcap 306 and a second O-ring. seal 313 is provided on the rear portion. The O-ring 312 forms a reciprocating seal on the interior ofcavity 283 ofpiston 277 and O-ring 313 forms a rotary seal on the counterbore offin sleeve 291. The 0-ring 285 inpiston 277 forms a reciprocating seal on the sidewall ofcap 306. - An
annular chamber 314 is formed between the exterior of the sidewall of thecap 306 and thecounterbore 283 which is sealed at each end by the O-rings sub 263 andcylinder cap 306 to reduce friction therebeween. The rear portion of the cap has a threadedbore 318 at the back end of thecap 306 which receives a hose fitting (not shown) and asmall passageway 319 extends inwardly from the threaded bore 318 to communicate theannular chamber 314 with a fluid or air source (not shown). A flexible hose extends outwardly of thecap 306 and is connected to the fluid or air source for effecting reciprocation of thepiston 277. - The operation of the
tail fin assembly 219 is best seen with reference to Figs. 18 and 19. Compressed air or fluid in theannular cavity 314 moves thepiston 277 to overcome the force of thespring 290 and move toward the front ofsub 263. In the foremost position, thedrive teeth passage 319 from the source into theannular chamber 314. Thefin sleeve 291 is then free to rotate relative to the tool body. - When the air or fluid pressure within the
chamber 314 is relieved, the force of thespring 290 moves thepiston 277 in the opposite direction (Fig. 19). During this movement, thedrive teeth fin sleeve 291 becomes locked against rotational movement relative to the tool body. The cycle may be selectively repeated as necessary for proper operation of the tool. - Figs. 20 and 21 are longitudinal cross sections of an alternate embodiment of the fixed/lockable fin assembly which incorporates a drive pin arrangement in place of one of the drive teeth members previously described. It will be noted that the drive pin arrangement necessitates moving the fin sleeve along the longitudinal axis to effect fin positioning.
- The
tail fin assembly 400 comprises acylindrical connecting sub 401 havingexternal threads 402 at the front end which are received within theinternal threads 32 at the rear portion of thebody 28. Thesub 401 has a first reduceddiameter portion 403 forming afirst shoulder 404 and a second reduceddiameter 405 adjacent the first forms asecond shoulder 406 which receives anannular seal 407. Therear portion 408 ofsub 401 is smaller in diameter than the second reduceddiameter 405 and extends longitudinally therefrom. - A thin
cylindrical retainer ring 409 is secured on the first reduceddiameter 403 of thesub 401 byscrews 410 and a smallannular rib 411 on the interior surface of the ring captures theseal 407 within thesecond shoulder 406. The rear end ofring 409 extends a short distance beyondseal 407 to surround the forward end of therear portion 408 of thesub 401. - An elongated, hollow cylindrical
rotating fin sleeve 412 is slidably and rotatably received within the extended portion ofring 409 and surrounds therear portion 408 ofsub 401. Thefin sleeve 412 has a centrallongitudinal bore 413 and acounterbore 414 of large diameter extending inwardly from the back end and defining anannular shoulder 415 therebetween. An O-ring seal 416 onfin sleeve 412 provides a rotary and reciprocating seal on the inner surface ofring 409. A plurality of circumferentially spaced dowel pins 417 extend radially inwardly through the side wall of thefin sleeve 412 and terminate a short distance from the circumference of therear portion 408 to thesub 401. An annular 0-ring seal 418 and abushing 419 is provided on the interior surface of thefin sleeve 412 intermediate the dowel pins 417 andshoulder 415. - A series of radially and angularly opposed
fins 420 are secured to the exterior of therotating fin sleeve 412 to extend radially outward therefrom. The fins are secured at opposing angles relative to the longitudinal axis of thesleeve 412 to impart a rotational force on the sleeve. An elongated hollowcylindrical cap 421 is slidably received on the subrear portion 408 withinfin sleeve 412 and secured to sub 401 by means of ascrew 422 at the rear portion thereof. Thecap 421 has a reduceddiameter front portion 423 and an enlarged diameterrear portion 424 forming ashoulder 425. A pair of longitudinally spaced O-rings 426 are positioned on therear portion 424 and abushing 427 is provided intermedi ate the O-rings 426. The enlarged diameterrear portion 424 of thecap 421 is rotatably received withincounterbore 414 with the O-rings 426 providing a rotary seal therebetween. - As shown in Figs. 20, 21, and 22, a series of
drive teeth 428 are formed on the front end of thecap 421. Thedrive teeth 428 comprise a series of circumferentially spaced raisedsurfaces 429, each having a generallystraight side 430 and an angularlysloping side 431 forming a one-way ratchet configuration. The spacing of thedrive teeth 428 relative to the dowel pins 417 is such that the pins will be retained by the teeth in the locked position to prevent rotary motion between thefin sleeve 412 andcap 421 as described hereinafter. - When properly positioned, an
annular chamber 432 is formed between theshoulder 415 of the fin sleeve and theshoulder 425 of the cap sealed at each end by the O-rings bore 433 at the back end of thecap 421 receives a hose fitting (not shown) and asmall passageway 434 extends inwardly from the threaded bore to communicate theannular chamber 432 with a fluid or air source (not shown) for reciprocatingfin sleeve 412. - The operation of the tail fin assembly with dowel pins is best seen with reference to Figs. 20, 21, and 22. Compressed air or fluid in the
annular chamber 432 moves thefin sleeve 412 toward the front of thesub 401. In the fore most position, the front end of thesleeve 412 contacts theseal 407 and the dowel pins 417 disengage from thedrive teeth 428. In this position (Fig. 20), compressed air or fluid is admitted through thepassage 434 from the source into theannular chamber 432. Thefin sleeve 412 is then free to rotate relative to the tool body. - When the air or fluid pressure within the
chamber 432 is relieved, the driving force of the tool hammer carries the tool including thecap 421 forward (Fig. 21). During this movement, driveteeth 428 and dowel pins 417 become engaged once again andfin sleeve 412 becomes locked against rotatianal movement relative to the tool body. The cycle may be selectively repeated as necessary for proper alignment of the slanted nose member and attitude adjustment of the tool. - Figs. 23 and 24 are partial longitudinal cross sections of variations of the fixed/4ockable fin assembly using a drive pin. The
tail fin assembly 500 comprises acylindrical connecting sub 501 havingexternal threads 502 at the front end which are received within theinternal threads 32 at the rear portion of thebody 28. Thesub 501 has a first reduceddiameter portion 503 forming ashoulder 504. Therear portion 505 of thesub 501 is smaller in diameter than the first reduced diameter forming asecond shoulder 506. Therear portion 505 extends longitudinally fromshoulder 506 and hasexterior threads 507 at the back end. - A thin
cylindrical retainer ring 508 is received on the reduceddiameter 503 ofsub 501 byscrews 509. The rear end ofring 508 extends a short distance beyond theshoulder 506 to surround the forward end of therear portion 505 of thesub 501. - An elongated hollow cylindrical rotating fin sleeve is slidably and rotatably received within the extended portion of
ring 508 and surrounds therear portion 505 ofsub 501. Thefin sleeve 510 has a centrallongitudinal bore 511 and acounterbore 512 of larger diameter extending inwardly from the back end and defining anannular shoulder 513. An 0-ring seal 514 on thefin sleeve 510 provides a rotary and reciprocating seal on the inner surface of thering 508. A plurality of circumferentially spaced dowel pins 505 extend radially inwardly through the side wall of thefin sleeve 510 and terminate a short distance from the circumference of therear portion 505 of thesub 501. An 0-ring seal 516 and abushing 517 are positioned on the interior surface offin sleeve 410 intermediate the dowel pins 515 andshoulder 513. - A plurality of radially and angularly opposed
fins 518 are secured to the exterior of therotating fin sleeve 510 and extend radially outward therefrom. Thefins 518 are secured at opposing angles relative to the longitudinal axis of thesleeve 510 to impart a rotational force on the sleeve. - A tubular cap 519 having a
central bore 520 and a threadedcounterbore 521 extending inwardly from the front end is slidably received on theair distribution tube 46 and the subrear portion 505 within thefin sleeve 510. The cap 519 is threadedly received and secured on thethreads 507 at the end of thesub 501. The cap 519 has a reduceddiameter front portion 522 and an enlarged diameterrear portion 523 forming ashoulder 524 therebetween. A pair of longitudinally spaced O-rings 525 are provided on therear portion 523 and abushing 526 is provided intermediate the O-rings 525. - The enlarged diameter
rear portion 523 of cap 519 is rotatably received within thecounterbore 512 with O-rings 525 providing a rotary seal. As previously shown and described with reference to Fig. 22, a plurality ofdrive teeth 428 are formed on the front end of the cap 519. Therear portion 523 of the cap 519 has a reduceddiameter portion 527 which removably receives aconical cover member 528. A plurality of circumferentially spacedlongitudinal bores 529 extend through the rear portion of the cap 519 for communicating the interior of thebody 28 with atmosphere. The drive teeth are constructed and operate as previously described for the other embodiments. - When properly positioned, an
annular chamber 530 is formed between theshoulder 513 of the fin sleeve and theshoulder 524 of the cap and sealed at each end by the O-rings bore 433 at the back end of the cap 519 receives a hose fitting (not shown) and asmall passage way 434 extends inwardly from the threaded bore to communicate theannular chamber 530 with a fluid or air source (not shown) for effecting reciprocation of thefin sleeve 510. - The operation of the tail fin assembly with dowel pins and drive teeth is best seen with reference to Figs. 23 and 24. Compressed air or fluid in the
annular chamber 530 moves thefin sleeve 510 toward the front of thesub 501. In its foremost position, the front end of thesleeve 510 contacts theshoulder 506 and the dowel pins 515 disengage from thedrive teeth 428. In this position - (Fig. 23), compressed air or fluid is admitted through thepassage 434 from the source into theannular chamber 530. Thefin sleeve 510 is then free to rotate relative to the tool body. - When the air or fluid pressure within the
chamber 530 is relieved, the driving force of the tool hammer carries the tool including the cap 519 forward (Fig. 24). During this movement, thedrive teeth 428 and dowel pins 515 engage once again and thefin sleeve 510 is locked aginst rotational movement relative to the tool body. The cycle may be selectively repeated as necessary for proper alignment of the slanted nose member and attitude adjustment of the tool. - Figs. 25 and 26 are partial longitudinal cross sectional views of a variation of the fixed/lockable fin assembly using an interlocking lug arrangement to prevent rota tional movement. The
tail fin assembly 600 comprises acylindrical connecting sub 601 having external threads at the front end which are received within the internal threads at the rear portion of the body (not shown). The circumference of thesub 601 has a first reduceddiameter portion 602 forming afirst shoulder 603. Therear portion 604 of thesub 661 is smaller in diameter than the first reduceddiameter 602 forming asecond shoulder 605. An annular raisedsurface 606 on therear portion 604 is spaced rearwardly from theshoulder 605 and provided with a series of circumferentially spacedslots 607 forming a series of raised lugs or splines 608. Therear portion 604 extends longitudinally from thelugs 608 and is provided withexterior threads 609 at the back end. An annular 0-ring seal 610 is provided on therear portion 604 inwardly of thethreads 609. - A thin
cylindrical retainer ring 508 is received on the first reduceddiameter 602 of thesub 601 byscrews 509. The rear end of thering 508 extends a short distance beyond theshoulder 605 to surround the forward end of therear portion 604 of thesub 601. - An elongated hollow cylindrical
rotating fin sleeve 611 is slidably and rotatably received within the extended portion of thering 508 and surrounds therear portion 604 of thesub 601. Thefin sleeve 611 has a centrallongitudinal bore 612, a front andrear counterbore annular shoulders ring seal 617 andannular bushing 618 are disposed oncentral bore 612 intermediate theshoulders diameter 619 is provided on the inner diameter of thefront counterbore 613 near the front end and provided with a series of circumferentially spacedslots 620 forming a series of raised lugs or splines 621. An O-ring seal 622 on the outer circumference of thefin sleeve 611 provides a rotary and reciprocating seal on the inner surface of thering 508. - A plurality of radially and angularly opposed
fins 518 are secured to the exterior of therotating fin sleeve 611 to extend radially outward therefrom. Thefins 518 are secured at opposing angles relative to the longitudinal axis of thesleeve 611 to impart a rotational force on the sleeve. - An elongated hollow
cylindrical cap 623 having acentral bore 624 and a larger threaded bore 625 extending inwardly from the front end is slidably received on theair distribution tube 46 and threadedly secured on thethreads 609 at the end of thesub 601. The outer circumference of thecap 623 is received within therear counterbore 614 of thefin sleeve 611. A pair of longitudinally spaced annular O-rings 626 are provided on the outer circumference of thecap 623 and abushing 627 is provided intermediate O-rings 626. The outer circumference of thecap 623 is rotatably received within thecounterbore 614 with the O-rings 626 providing a rotary seal therebetween. The rear portion of thecap 623 has a reduceddiameter portion 628 which removably receives a conical cover member 629. A plurality of circumferentially spacedlongitudinal bores 630 extend through the rear portion of the cap for communicating the interior of the tool body with atmosphere. - When properly positioned, an
annular chamber 631 is formed between theshoulder 616 of the fin sleeve and the forward end of thecap 623 and sealed at each end by the O-rings bore 433 at the back end of thecap 623 receives a hose fitting (not shown) and asmall passageway 434 extends inwardly from the threaded bore to communicate theannular chamber 631 with a fluid or air source (not shown) for effecting reciprocation of the fin sleeve. - The operation of the
tail fin assembly 600 is best seen with reference to Figs. 25 and 26. Under action of compressed air or fluid in theannular chamber 631 thefin sleeve 611 begins to move toward the front of thesub 601. When in its foremost position, the front end of thesleeve 611 contacts theshoulder 605 and thelugs passage 434 from the source into theannular chamber 631. Thefin sleeve 611 is then free to rotate relative to the tool body. - When the air or fluid pressure within the
chamber 631 is relieved, the driving force of the too! hammer carries the tool including thecap 623 forward (Fig. 26). During this movement, the drive lugs orsplines fin sleeve 611 becomes locked against rotational movement relative to the tool body. The cycle may be selectively movement relative to the tool body. The cycle may be safer-- tivety repeated as necessary for proper alignment of the slanted nose member and attitude adjustment of the tool. - Figs. 27 and 28 are partial longitudinal cross sections of another variation of the fixedaockable fin assembly using a drive pin. The
tail fin assembly 650 comprises acylindrical connecting sub 651 havingexternal threads 652 at the front end which are received within theinternal threads 32 at the rear portion of thebody 28. Therear portion 653 of thesub 651 is smaller in diameter than the front portion forming ashoulder 654. Therear portion 653 extends longitudinally from theshoulder 654 and hasinterior threads 655 at the back end. - A thin
cylindrical retainer ring 656 is received on the front portion of thesub 651 between a raisedshoulder 657 and the back end of thebody 28. The rear end of thering 656 extends a short distance beyond the raisedshoulder 657 to surround the forward end of therear portion 653 of thesub 651. A plurality of circumferentially spaced dowel pins 417 extend radially outward through the side wall of therear portion 653 and terminate a short distance from the interior surface of thering 656. - An elongated hollow cylindrical
rotating fin sleeve 659 is slidably and rotatably received within the extended portion of thering 656 and surrounds therear portion 653 of thesub 651 including the dowel pins 417. Thefin sleeve 659 has a centrallongitudinal bore 660 and acounterbore 661 of larger diameter extending inwardly from the back end and defining anannular shoulder 662 therebetween. An O-ring seal 663 on the outer circumference. of thefin sleeve 659 provides a rotary and reciprocating seal on the inner surface of thering 656. An annular O-ring seal 664 and a pair ofbushings 665 are provided on the interior surface of thefin sleeve 659. A plurality of drive teeth 428 - (as previously shown and described) are formed on the front end of thefin sleeve 659. - A plurality of radially and angularly opposed
fins 666 are secured to the exterior of therotating fin sleeve 659 to extend radially outward therefrom. Thefins 666 are secured at opposing angles relative to the longitudinal axis of thesleeve 659 to impart a rotational force on the sleeve. - An elongated hollow
cylindrical cap 667 having acentral bore 668 and acounterbore 669 extending inwardly from the front end is slidably received on the airdistri bution tube 46 within thefin sleeve 659.Exterior threads 670 are provided on the front portion of thecap 667 which are received on thethreads 655 at the back end of thesub 651. The rear portion of thecap 667 is larger in diameter than the threaded front portion forming ashoulder 671 therebetween. - A pair of longitudinally spaced annular O-
rings 672 are provided on the outer circumference of the rear portion and abushing 673 is provided intermediate the O-rings. The enlarged diameter rear portion of thecap 667 is rotatably received within thecounterbore 661 with the O-rings 672 providing a rotary seal therebetween. The rear portion of thecap 667 removably receives aconical cover member 674. To avoid repetition, the detailed description of the drive teeth and their operation will not be repeated here. - When properly positioned, an
annular chamber 675 is formed between theshoulder 662 of the fin sleeve and theshoulder 671 of the cap and sealed at each end by the O-rings bore 433 at the back end of thecap 667 receives a hose fitting (not shown) and asmall passageway 434 extends inwardly from the threaded bore to communicate theannular chamber 675 with a fluid or air source (not- shown) for effecting reciprocation of thefin sleeve 659. Fig. 28 shows the locked position, and since the operation of the tail fin assembly has been previously shown and explained, it will not be repeated here. - Figs. 29 and 30 are partial longitudinal cross sections of another variation of the fixed/lockable fin assembly using a series of slots or splines and dowel pins to prevent rotational movement. The
tail fin assembly 700 comprises acylindrical connecting sub 701 havingexternal threads 702 at the front end which are received within theinternal threads 32 at the rear portion of thebody 28. The circumference of thesub 701 has a first reduceddiameter portion 703 forming afirst shoulder 704 therebetween. A second reduceddiameter 705 forms asecond shoulder 706. A thirdreduced diameter 707 forms a thirdreduced diameter 708. An enlarged diameter 709 approximately the same diameter as the second is spaced therefrom and provided with a series of circumferentially spacedslots 710 defining a series of raised lugs orsplines 711 on the thirdreduced diameter 707. Afourth diameter 712 smaller than the third forms afourth shoulder 714 therebetween. Thefourth diameter 712 extends longitudinally from the shoulder-714 and is provided withexterior threads 715 at the back end. - A thin
cylindrical retainer ring 716 is received on the first reduceddiameter 703 of thesub 701 byscrews 717. The rear end of thering 716 extends a short distance beyond theshoulder 706 to surround the forward end of the reduceddiameter 705. Arod wiper 718 is contained on the interior of the rear end of thering 716. - An elongated hollow cylindrical
rotating fin sleeve 719 is slidably rotatably received within the extended portion of thering 716 and surrounds the rear portion of thesub 701. Thefin sleeve 719 has a centrallongitudinal bore 720, a front andrear counterbore annular shoulders annular bushing 725 is disposed on the inner diameter of thecounterbore 721 and arod wiper 726 is provided on the inner diameter of thecounterbore 722. A plurality of circumferentially spaced dowel pins 727 extend radially inwardly through the side wall of thefin sleeve 719 and terminate a short distance from the circumference of the thirdreduced diameter 707 of thesub 701. An annular bushing 728 is provided on thecentral bore 720 intermediate theshoulders - A plurality of radially and angularly opposed
fins 729 are secured to the exterior of therotating fin sleeve 719 to extend radially outward therefrom. Thefins 729 are secured at opposing angles relative to the longitudinal axis of thesleeve 719 to impart a rotational force on the sleeve. - An elongated hollow
cylindrical cap 730 having acentral bore 731 provided withinterior threads 732 and acounterbore 733 extending inwardly from the front end is received on thethreads 715 of thesub 701 and within thecounterbore 722 of thefin sleeve 719. An annular 0-ring 734 on thebore 731 provides a seal on the fourth reduceddiameter 712 of thesub 701. Acylindrical reciprocating piston 735 is slidably reeived on the fourth reduceddiameter 712 of thesub 701 and within thecounterbore 733 of thecap 730. Annular O-rings piston 735. - With the
piston 735 properly positioned, anannular chamber 736 is formed between the fourth reduceddiameter 712 and thecounterbore 733 and sealed at each end by the 0-rings bore 433 at the back end of thecap 730 receives a hose fitting (not shown) and asmall passageway 434 extends inwardly from the threaded bore to communicate theannular chamber 736 with a fluid or air source (not shown) for effecting reciprocation of thepiston 735 andfin sleeve 719. - The operation of the
tail fin assembly 700 is best seen with reference to Figs. 29 and 30. Under action of compressed air or fluid in theannular chamber 736 thepiston 735 begins to move toward the front of thesub 701 and contacts theshoulder 724 of thefin sleeve 719 carrying it forward. When in its foremost position, the front end of thepiston 735 contacts theshoulder 714 and the dowel pins 727 become disengaged from the slots or splines 810. In this position (Fig. 29), compressed air or fluid is admitted through thepassage 434 from the source into theannular chamber 736. Thefin sleeve 719 is then free to rotate relative to the tool body. - When the air or fluid pressure within the
chamber 736 is relieved, the driving force of the tool hammer carries the tool including thesub 701 forward relative to the fin sleeve 719 (Fig. 24). During this movement, theshoulder 724 moves the piston rearwardly and the dowel pins 727 become engaged once again in theslots 710 and thefin sleeve 719 becomes locked against rotational movement relative to the tool body. The cycle may be selectively repeated as necessary for proper alignment of the slanted nose member and attitude adjustment of the tool. - Figs. 31 and 32 are partial longitudinal cross sections of another variation of the fixed/lockable fin assembly using a series of slots or splines and dowel pins to prevent rotational movement The
tail fin assembly 750 comprises acylindrical connecting sub 751 havingexternal threads 752 at the front end which are received within theinternal threads 32 at the rear portion of thebody 28. The circumference of thesub 751 has a first reduceddiameter portion 753 forming afirst shoulder 754 therebetween. A second reduceddiameter 755 forms asecond shoulder 906. A thirdreduced diameter 757 forms athird shoulder 758. Anenlarged diameter 759 approximately the same diameter as the second is spaced therefrom and provided with a series of circumferentially spacedslots 760 defining a series of raised lugs orsplines 761 on the thirdreduced diameter 757. Thethird diameter 757 extends longitudinally from the lugs orsplines 761 and is provided withexterior threads 762 at the back end. - A thin
cylindrical retainer ring 763 is received on the first reduceddiameter 753 of thesub 751 byscrews 754. The rear end of thering 763 extends a short distance beyond the shoufder-756 to surround the forward end of the reduceddiameter 755. Arod wiper 765 is contained on the interior of the rear end of thering 763. - An elongated hollow cylindrical
rotating fin sleeve 766 is slidably and rotatably received within the extended portion of thering 763 and surrounds the rear portion of thesub 751. Thefin sleeve 766 has a centrallongitudinal bore 767, a front andrear counterbore annular shoulders annular bushing 772 is disposed on the inner diameter of thecounterbore 768 and arod wiper 773 is provided on the inner diameter of therear counterbore 769. A plurality of circumferentially spaced dowel pins 774 extend radially inwardly through the side wall of thefin sleeve 766 and terminate a short distance from the circumference of the thirdreduced diameter 757 of thesub 751. - A plurality of radially and angularly opposed
fins 775 are secured to the exterior of therotating fin sleeve 766 to extend radially outward therefrom. Thefins 775 are secured at opposing angles relative to the longitudinal axis of thesleeve 766 to impart a rotational force on the sleeve. - An elongated hollow
cylindrical cap 776 having acentral bore 777 provided withinterior threads 778 and a counterbore 779 extending inwardly from the front end is received on thethreads 762 of thesub 751 and within thecounterbore 769 of thefin sleeve 766. An annular 0-ring 780 on thebore 777 provides a seal on the thirdreduced diameter 757 of thesub 751. Anannular bushing 781 is provided on the circumference of thecap 776. Acylindrical reciprocating piston 782 is slidably received on the thirdreduced diameter 757 of thesub 751 and within thecounterbore 769 of thecap 776. A reduceddiameter 783 at the front end of the piston is received within thecentral bore 767 of thefin sleeve 766. Annular O-rings piston 781. - With the
piston 781 properly positioned, anannular chamber 786 is formed between the circumference of thesub 751 and thecounterbore 777 and sealed at each end by the O-rings bore 433 at the back end of thecap 786 receives a hose fitting (not shown) and asmall passageway 434 extends inwardly from the threaded bore to communicate theannular chamber 785 with a fluid or air source (not shown) for effecting reciprocation of thepiston 782 andfin sleeve 766. - The operation of the
tail fin assembly 750 is best seen with reference to Figs. 31 and 32. Under action of compressed air or fluid in theannular chamber 786 thepiston 782 begins to move toward the front of thesub 751 and carries thefin sleeve 766 with it. When in its foremost position, the front end of thepiston 782 contacts the lugs orsplines 761 and the dowel pins 774 become disengaged from theslots 760. In this position (fig. 31), compressed air or fluid is admitted through thepassage 434 from the source into theannular chamber 786. Thefin sleeve 766 is then free to rotate relative to the tool body. - When the air or fluid pressure within the
chamber 786 is relieved, the driving force of the tool hammer carries the tool including thesub 751 forward relative to the fin sleeve 766 (Fig. 32). During this movement, theshoulder 771 moves the piston rearwardly and the dowel pins 774 become engaged once again in the slots orsplines 760 and thefin sleeve 766 becomes locked against rotational movement relative to the tool body. The cycle may be selectively repeated as necessary for proper alignment of the slanted nose member and attitude adjustment of the tool. - Figs. 33 and 34 are partial longitudinal cross sections of another variation of the fixed/lockable fin assembly using a series of dowel pins and drive teeth to prevent rotational movement. The
tail fin assembly 800 comprises acylindrical connecting sub 801 havingexternal threads 802 at the front end which are received within the internal threads at the rear portion of the tool body. The circumference of thesub 801 has a first reduceddiameter portion 803, and a second reduced diameter 804 forms ashoulder 805 therebetween. A third reduced diameter 806 forms a third shoulder 807. The third diameter 806 extends longitudinally from the shoulder 807 and is provided withexterior threads 808 at the back end. - A thin
cylindrical retainer ring 809 is received on the first reduceddiameter 803 of thesub 801 byscrews 810. The rear end of thering 809 extends a short distance beyond theshoulder 805 to surround the forward end of the reduced diameter 804. Arod wiper 811 is contained on the interior of the rear end of thering 809. - An elongated hollow cylindrical
rotating fin sleeve 812 has a centrallongitudinal bore 813, and arear counterbore 814 of larger diameter extending inwardly from the back end and defining anannular shoulder 815 therebetween. Anannular bushing 816 is provided on the central bore and another bushing 817 is provided on thecounterbore 814. The outer circumference of thefin sleeve 812 is provided with front reduceddiameter 818 and a rear reduceddiameter 819. Thefin sleeve 812 is slidably and rotatably received on thesub 801 with thecentral bore 813 on the second reduced diameter 804 and the front reduceddiameter 818 within the extended portion of thering 809. A series ofdrive teeth 428 previously shown and described with reference to Fig. 22 are formed on the back end of thefin sleeve 812. - A plurality of radially and angularly opposed
fins 820 are secured to the exterior of therotating fin sleeve 812 to extend radially outward therefrom. Thefins 820 are secured at opposing angles relative to the longitudinal axis of thesleeve 812 to impart a rotational force on the sleeve. - An elongated hollow
cylindrical cap 821 having a central bore 822 provided withinterior threads 823 and acounterbore 824 extending inwardly from the front end and defining a shoulder 825 therebetween is received on thethreads 808 of the sub and within thecounterbore 814 of thefin sleeve 812. An annular 0-ring 826 on the bore 822 provides a seal on the third reduced diameter 806 of thesub 801, and another O-ring 827 on thecounterbore 814 provides a seal on the reduced portion of a piston member described hereinafter. A plurality of circumferentially spaced dowel pins 828 extend radially outward through the side wall of the fin sleeve 812 (shown out of position). - A
cylindrical reciprocating piston 829 is slidably received on the third reduced diameter 806 of thesub 801. Therear portion 830 of thepiston 829 is smaller in diameter than the outer circumference defining ashoulder 831 therebetween. The outer circumference of thepiston 829 is received in the annulus between the third reduced diameter 806 and thefin sleeve counterbore 814 and therear portion 830 is received in the annulus between the third reduced diameter 806 andcounterbore 824 of thecap 821. An annular 0-ring 832 is provided on the inner diameter of thepiston 829. With thepiston 829 properly positioned, anannular chamber 833 is formed between the back end of the piston and thecounterbore 824 of thecap 821 and sealed by the O-rings - A threaded
bore 433 at the back end of thecap 821 receives a hose fitting (not shown) and asmall passageway 434 extends inwardly from the threaded bore to communicate theannular chamber 833 with a fluid or air source (not shown) for effecting reciprocation of thepiston 829 andfin sleeve 812. - A second thin
cylindrical retainer ring 834 is secured on the rear reduceddiameter 819 of thefin sleeve 812 byscrews 835 and extends rearwardly to surround thedrive teeth 428 and the dowel pins 828. The rear end of thering 834 extends a distance beyond the dowel pins 828 and is provided with arod wiper 836. - The operation of the
tail fin assembly 800 is best seen with reference to Figs. 33 and 34. Under action of compressed air or fluid in theannular chamber 833 thepiston 829 begins to move toward the front of thesub 801 contacting theshoulder 815 and carrying thefin sleeve 812 with it. When in its foremost position, the front end of thepiston 829 contacts theshoulder 815 and the drive teeth ecome disengaged from the dowel pins 828. In this position (Fig. 33), compressed air or fluid is admitted through thepassage 434 from the source into theannular chamber 833. Thefin sleeve 812 is then free to rotate relative to the tool body. - When the air or fluid pressure within the
chamber 833 is relieved, the driving force of the tool hammer carries the tool including thesub 801 forward relative to the fin sleeve 812 (Fig. 34). During this movement, theshoulder 815 moves the piston rearwardly and thedrive teeth 428 become engaged once again with the dowel pins 828 and thefin sleeve 812 becomes locked against rotational movement relative to the tool body. The cycle may be selectively repeated as necessary for proper alignment of the slanted nose member and attitude adjustment of the tool. - Fig. 35 is a longitudinal cross sectional view of a movable tail fin assembly. Fig. 36 is a vertical cross sectional view of the movable tail fin assembly of Fig. 35 taken along line 36 -36 of Fig. 35. The movable tail fin arrangement is similar to the fixed/lockable tail fins previously described with the exception that it rotates the boring tool through an inclined, anti-parallel or skewed fin arrangement. When the two fins are parallel, the soil forces acting on their faces prevents rotation of the tool housing and allows the nose member or eccentric hammer to produce a net deflective force which causes the tool to veer in a curved trajectory.
- The movable
tail fin assembly 900 comprises acylindrical connecting sub 901 having external threads at the front end which are received within the internal threads at the rear portion of the tool body. The outer rear portion of thesub 901 is reduced in diameter defining ashoulder 902 and provided with external threads 903. A series of circumferentialy spacedopenings 904 extend radially through the side wall of thesub 901 communicating the interior of the tool to atmosphere. A pair of opposed J-slots 905 extend longitudinally inward from the back end of thesub 901 and terminate a distance from theopenings 904. - An annular O-
ring seal 906 on the centaI bore 90 provides a seal on theair distribution tube 46. Acircular opening 908 extends transversly through the rear portion of thesub 901 and the J-slots 905. In annulararcuate groove 909 is formed in the interior of eachcircular opening 908 spaced outwardly from each side of theslots 905 and concentric with theopening 908, and asmall opening 910 extends from each groove to the outer surface of thesub 901. The openings are used to fill the grooves withball bearings 911 after which they are enclosed by threadedplugs 912 - A
piston spool 913 is slidably received on theair distribution tube 46. Thepiston spool 913 comprises an elongated cylindrical member having a centrallongitudinal bore 914 with an 0-nng seal 915 near the back end to seal on thetube 46. The front portion of thespool 913 is in the form of atubular extension 916 and has a short reduceddiameter 917 at the forward end. The rear portion of the spool has anenlarged diameter 918 greater than theextension 916 to define ashoulder 919 therebetween. An O-ring seal 920 is provided on theenlarged diameter 918. A pair of radially opposed threadedbores spool 913 to receive hose fittings for connection to an air or fluid source (not shown). - A cylindrical piston 923 having a
central bore 924 is slidably mounted on the circumference of thetubular extension 916. A pair of radtWLly opposedbores bores internal threads 927 at the rear portion. An O-ring seal 928 disposed in thecentral bore 924 provides a reciprocating seal on thetubular extention 916. Another O-ring seal 929 is provided on the circumference of the piston 923. - A cylindrical bulkhead 930 having a
central bore 931 is mounted on the forward end of thetubular extension 916. A pair of radially opposedbores 932 and 933 in axial alignment with thebores ring seal 935 disposed in thecentral bore 931 provides a seal ontubular extension 916. Another O-ring seal 936 is provided on the circumference of the bulkhead 930. Aslot 937 extends vertically through one side wall of the bulk head at the forward end and receives arectangular key 938 for keying the bulkhead to the back end ofsub 901. - An
actuating rod 939 having a flat rectangularfront portion 940 and a longitudinally offset roundtail portion 941 is carried by the piston 923. The front portion of theactuating rod 939 is slidably recived in the elongated portion of the J-slot 905 and thetail portion 941 extends outwardly therefrom to be slidably received through the bulkhead bore 932 and provided with external threads at the rear end which are received on thethreads 927 of thebore 925 in the piston 923. The rectangularfront portion 940 is provided with atransverse slot 942 which engages the protruding lug of a cup- shaped member. described hereinafter. An O-ring seal 948 is disposed on the circumference of thetail portion 941 to provide a seal on the piston bore 925. - Similarly, a longer,
reverse actuating rod 943 having a flat rectangularfront portion 944 and a longitudinally offset roundtail portion 943 is carried by the piston 923. The front portion of theactuating rod 943 is slidably recived in the elongated portion of the opposing J-slot 905 and thetail portion 945 extends outwardly therefrom to be slidably received through the opposed bulkhead bore 933 and provided with external threads which are received on thethreads 927 of thebore 926 in the piston 923. A reduceddiameter 946 extends rearwardly from thethreads 927 and is slidably received within thebore 922 of thepiston spool 913. The rectangularfront portion 944 is provided with atransverse slot 947 which engages the protruding lug of another cupshaped member (hereinafter described). An O-ring seal 948 is disposed on the circumference of thetail portion 945 to provide a seal on the piston bore 926. - An elongated hollow cylindrical
outer sleeve 949 is slidably received on the outer periphery of the bulkhead 930, the piston 923, and thepiston sleeve 913. Theouter sleeve 949 hasinterior threads 950 at the front portion, a centrallongitudinal bore 951 extending therefrom and terminating at a reduced bore 952 defining anannular shoulder 953 therebetween. Theouter sleeve 949 is threadedly received on the threaded portion of thesub 901 with aseal 954 provided between the front end and thesub shoulder 902. A pair ofcircular openings 955 extend transversly through the side wall of the sleeve in axial alignment with theopening 908 to receive the cup-shaped members - (described hereinafter). The reduced bore 952 is received on a short reduceddiameter 956 of thepiston spool 913 and the O-rings central bore 951. - In this manner, the above mentioned components are enclosed, and the side wall of the sleeve forms a sealed
front chamber 957 between the bulkhead 930 and the piston 923. A secondrear chamber 958 is formed between the piston 923 and thepiston sleeve 913. Asmall passageway 959 extends inwardly from the back end of thereverse actuating rod 943 and communicates thebore 922 of thepiston sleeve 913 with thefront chamber 957. The opposed bore 921 of thepiston sleeve 913 is in communication with therear chamber 958. It should be understood that the opposed bores 921 and 922 at the back end of the piston sleeve receive hose fittings and flexible hoses extend outwardly therefrom and to be connected to the fluid or air source for effecting reciprocation of the piston. - A pair of steering
fins rectangular fin 962 secured to a cylindrical cup-shapedmember circular openings ring seal 965 to provide a rotary seal on the interior of theopening 908, and a circumferentialarcuate groove 966 in alignment with thegrooves 909 to receive theball bearings 911. After thebearings 911 are placed in the grooves, the tail fins are locked against outward movement, and are free to rotate about the transverse axis within the openings. The opposed cylindrical ends of the cup-shapedmembers sub 901. - In arcuate eliptical cut-away portion extends transversely across the ends of each cup-shaped member leaving a flat raised
segment 967 and a dimetrically opposed protrudinglug 968 which is disposed angularly relative to the longitudinal axis of therectangular fin 962. In this manner, when the cylindrical ends are in contact, thelugs 968 are diametrically opposed and the elliptical opening surrounds theair distribution tube 46, whether the fins are rotated to a postition parallel or angularly disposed relative to the longitudinal axis of the tool. One lug is received in theslot 942 of the actuating rod and the opposing lug is received within theslot 947 of the reverse actuating rod. - The operation of the movable tail fin assembly is best seen with reference to Figs. 35, 37, and 38. Under action of compressed air or fluid in the
front chamber 957, the piston 923 moves toward the back of thesub 901 carrying the actuatingrods members rear chamber 958 has been relieved or exhausted. In this position (Fig. 35), the fins are positioned angularly relative to the longitudinal axis of the tool body. When the two fins are inclined in opposite directions, the soil forces acting on their faces causes the tool housing to rotate about its longitudinal axis and the toot bores in a straight direction. - When the air or fluid pressure within the
rear chamber 958 is relieved, thefront chamber 957 is pressurized to move the pistons in the opposite direction (Figs. 37 and 38). In this position, the fins are positioned parallel to the longitudinal axis of the tool body. In this position, the fins prevent rotation of'the tool housing and the tool bores in a curved direction as a result of the asymmetric boring force of the slanted nose member or the eccentric hammer. - The positioning of the fins in parallel or anti-parallel positions may be selectively changed as necessary for proper alignment and attitude adjustment of the tool.
- Figs. 40 and 41 are longitudinal cross sections of a portion of a boring tool including an eccentric hammer arrangement. An off-axis or eccentric hammer may be used in combination with the tail fin arrangements described previously. When the center of mass of the hammer is allowed to strike the inner anvil at a point radially offset from the longitudinal axis of the tool, a deflective side force results. This force causes the boring tool to deviate in the direction opposite to the impact point as depicted in Fig. 40. Orientation may be controlled by the external rotation of the tool body with tail fins. The only internal modification required is the replacement of the existing hammer.
- Fig. 40 shows the front portion details of a
boring tool 23 which was shown previously in - schematic form in Fig. 8 with a movable tail fin system in combination with aneccentric hammer 24. The rear portion of thehammer 24 is not shown, with the understanding that the rear portion of thehammer 24 would be the same as theconcentric hammer 37 shown in Fig. 9B. The rear portion of the tool is not shown in Figs. 40 or 41 since the eccentric hammer may be used in combination with either the fixed/lockable fin systems or the movable fin systems and with or without the slanted nose member previously shown and described. - Referring now to Figs. 40, 41 and 9B, the
boring tool 23 comprises an elongated hollow cylindrical outer housing orbody 25. The outer front end of thebody 25 tapers inwardly forming aconical portion 29. The internal diameter of thebody 23 tapers inwardly near the front end forming aconical surface 30 which terminates in a reduceddiameter 31 extending longitudinally inward from the front end. The rear end of the body is provided with intemal threads for receiving a tail fin assembly previously described. - An
anvil 33 having aconical back portion 34 and an elongated cylindricalfront portion 35 is contained within the front end of thebody 23. Theconical back portion 34 of theanvil 33 forms and interference fit on theconical surface 30 of thebody 23, and the elongatedcylindrical portion 35 extends outwardly a distance beyond the front end of the body. Aflat surface 36 at the back end ofanvil 33 receives the impact ofeccentric reciprocating hammer 24. - A
slanted nose member 18 having a cyUnd,6cal back portion 52 and a central cylindrical bore 53 extending inwardly therefrom may be secured on thecylindrical portion 35 of the anvil 33 (Fig. 40). Aslot 54 through the sidewall of thecylindrical portion 51 extends longitudinally substantially the length of thecentral bore 53 and. atransverse slot 55 extends radially from thebore 53 to the outer circumference of the cylindrical portion, providing flexibility to the cylindrical portion for clamping the nose member to the anvil. Longitudinally spaced holes in alignment with threadedbores 58 on the opposing side of theslot 54 receivescrews 59 which secure thenose member 18 to theanvil 33. The sidewall of thenose member 18 extends forward from thecylindrical portion 52 and one side is milled to form a flatinclined surface 60. - The
eccentric hammer 24 is an elongated cylindrical member slidably received within theinternal diameter 38 of thebody 23. A substantial portion of the outer diameter of thehammer 24 is smaller in diameter than theinternal diameter 38 of the body, forming anannular cavity 39 therebetween. The front portion of the hammer is constructed in a manner to offset the center of gravity of the hammer with respect to its longitudinal axis. As shown in Fig. 40, the side wall of the hammer is provided with alongitudinal slot 970 which places the center of mass eccentric to the iongitudtna! axis and thefront surface 43 of the front end of thehammer 24 is shaped to provide an impact centrally on theflat surface 36 of theanvil 33. In Fig. 41, the side wall of thehammer 24a is provided with alongitudinal slot 970 and thefront surface 43a is radially offset from the longitudinal axis to place the center of mass eccentric to the longitudinal axis and thereby deliver an eccentric impact force on the anvil. - A series of longitudinal circumferentially spaced
slots 972 are provided on the outer surface of the front of the hammer to allow passage of air or fluid from the front end to the reduced diameter portion. - In order to assure proper orientation of the hammer, a key or
pin 26 is secured through the side wall of thebody 25 to extend radially inward and be received within theslot 970 to maintain the larger mass of the hammer on one side of the longitudinal axis of the tool. - As shown in Fig. 9C, a relatively
shorter portion 40 at the back end of thehammer 37 is of larger diameter to provide a sliding fit against theinterior diameter 38 of the body. Acentral cavity 41 extends longitudinally inward a distance from the back end of thehammer 37. Acylindrical bushing 42 is slidably disposed within thehammer cavity 41, the circumference of which provides a sliding fit against the inner surface of thecentral cavity 41. -
Air passages 44 are provided through the sidewall of thehammer 37 inwardly adjacent the shorterrear portion 40 to communicate thecentral cavity 41 with theannular cavity 39. Anair distribution tube 45 extends centrally through thebushing 42 and itsback end 46 extends outwardly of thebody 28 and is connected byfittings 47 to a flexible hose 48. For effecting reciprocation of thehammer 37, theair distribution tube 45 is in permanent communication with a compressed air source (not shown). The arrangement of thepassages 44 and thebushing 42 is such that, during receiproca- tion of thehammer 37, theair distribution tube 45 alternately communicates via thepassages 44, theannular cavity 39 with either thecentral cavity 41 or atmosphere at regular intervals. - A
cylindrical stop member 49 is secured within the inner diameter of thebody 28 near the back end and is provided with a series of longitudinally extending, circumferentially spacedpassageways 50 for communicating the interior of thebody 28 with atmosphere. Theair distribution tube 45 is centrally disposed within thestop member 49. - Under action of compressed air in the
central cavity 41, thehammer 24 moves toward the front of thebody 25. When in its foremost position, the hammer imparts an impact on theflat surface 36 of theanvil 33. In this position, compressed air is admitted through thepassages 44 from thecentral cavity 41 into theannular cavity 39. Since the effective area of the hammer including the larger diameterrear portion 40 is greater than the effective area of thecentral cavity 41, the hammer starts moving in the opposite direction. During this movement, thebushing 42 closes thepassages 44, thereby interruputing the admission of compressed air intoannular cavity 41. Thehammer 37 continues its movement due to the expansion of the the air in theannular cavity 39 until thepassages 44 are displaced beyond the ends of thebushing 42, and the annular cavity is placed to communication to atmosphere through theholes 50 in thestop member 49. In this position, the air is exhausted from theannular cavity 39 through thepassages 44 now above the trailing edge of thebushing 42 and theholes 50 in thestop member 49. Then the cycle is repeated. - The eccentric hammer can be used for straight boring by averaging the deflective side force over 360° by rotating the outer body. The fins provide orientation capabilities as previously described and are brought into an unlocked rotating or straight parallel alignment position when executing turns. Straight boring of the tool is accomplished by activating the fins to a spin inducing position counteracting the tendency of the eccentric hammer to turn the tool.
- When the fins are in a position preventing the tool housing from rotating the tool will turn under the influence of the asymmetric boring forces. Either an eccentric hammer or anvil will produce the desired result, since the only requirement is that the axis of impact does not pass through the frontal center of pressure.
- This embodiment consists of an overgage sleeve or sleeves located over a portion of the tool outer surface which are affixed such that they can rotate but cannot slide axially. This permits transmittal of the tool's axial impact force from the tool to the soil while allowing free rotation of the tool during spinning operations. The overgage areas are at the front and back of the tool, or alternately, an undergage section in the center of the tool body. This undercut in the center of the tool permits a 2- point contact (front and rear) of the tool's outer housing with the soil wall as opposed to the line contact which occurs without the undercut. The 2- point contact allows the tool to deviate in an arc without distorting the round cross-sectional profile of the pierced hole. Thus, for a given steering force at the front and/or back of the tool, a higher rate of turning is possible since a smaller volume of soil is displaced.
- In Fig. 42, there is shown a preferred guided horizontal
boring tool 1010, having overgage body sections, used with a magnetic field attitude sensing system. Theboring tool 1010 may be used with various sensing systems, and a magnetic attitude sensing system is depicted generally as one example. The usual procedure for using percussion moles is to first locate and prepare the launching and retrieval pits. The launching pit P should be dug slightly deeper than the planned boring depth and large enough to provide sufficient movement for the operator. Theboring tool 1010 is connected to a pneumatic orhydraulic source 11, is then started in the soil, stopped and properly aligned, preferably with a sighting frame and level. The tool is then restarted and boring continued until the tool exists into the retrieval pit (not shown). - The
boring tool 1010 may have a pair ofcoils 12, shown schematically at the back end, one of which produces a magnetic field parallel to the axis of the tool, and the other produces a magnetic field transverse to the axis of the tool. These coils are intermittently excited by alow frequency generator 13. To sense the attitude of the tool, twocoils - Outputs of these coils can be processed to develop the angle of the tool in both the horizontal and vertical directions with respect to the boresite axis. Using the transverse field, the same set of coils can be utilized to determine the angular rotation of the tool to provide sufficient control for certain types of steering systems. For these systems, the angular rotation of the tool is displayed along with the plane in which the tool is expected to steer upon actuation of the guidance control system.
- The mechanical guidance of the tool can also be controlled at a
display panel 16. From controls located atdisplay panel 16, both the operation of thetool 1010 and the pneumatic or hydraulic actuation of thefins 1017 can be accomplished as described hereinafter. - As shown in Fig. 42, the
boring tool 1010 includes a steering system comprising a slanted-face nose member 1018 attached to theanvil 1033 of the tool to produce a turning force on the tool andtail fins 1017 on arotary housing 1019a on the trailing end of the tool which are adapted to be selectively positioned relative to the body of the tool to negate the turning force. Turning force may also be imparted to the tool by an intemal eccentric hammer, as shown in Fig. 41, above, delivering an off-axis impact to the tool anvil. - For turning the tool, the
tail fins 1017 are moved into a position where they may spin about the longitudinal axis of thetool 1010 and theslanted nose member 1018 or eccentric hammer will deflect the tool in a given direction. When thefins 1017 are moved to a position causing thetool 1010 to rotate about its longitudinal axis, the rotation, will negate the turning effect of thenose member 1018 or eccentric hammer as well as provide a means for orienting the nose piece into any given plane for subsequent turning or direction change. - The body of the
tool 1010 hasfront 1021 and rear 1022 overgage body sections which give improved performance of the tool in angular or arcuate boring. These overgage sections are fixed longitudinally on the tool body and may be fixed against rotation or may be mounted on bearings which permit them to rotate. - The steering system of the present invention will allow the operator to avoid damaging other underground services (such as power cables) or to avoid placing underground utilities where they may be damaged. The body construction of the tool including the overgage sections cooperates with the steering mechanism to give overall improved performance.
- Figs. 43 through 46 illustrate various embodiments of the boring tool with overgage sections on the tool body. In Fig. 43. there is shown a
boring tool 1010 having abody 1020 enclosing the percussion mechanism driving the tool. The front end ofbody 1020 is tapered as at 1029 and has theexternal portion 1035 of the anvil protruding therefrom for percussion boring. -
Front sleeve 1021 andrear sleeve 1022 are mounted on tool body orhousing 1020 by a shrink or interference fit In this embodiment,overgage sleeves - In Fig. 44, there is shown another embodiment of the boring tool in which one of the overgage sleeves is free to rotate. In this embodiment,
boring tool 1010 has abody 1020 enclosing the percussion mechanism driving the tool. The front end ofbody 1020 is tapered as at 1029 and has theexternal portion 1035 of the anvil protruding therefrom for percussion boring. -
Front sleeve 1021 is mounted on tool body orhousing 1020 by a shrink or interference fit. Theovergage sleeve 1021 is fixed against longitudinal or rotational slippage. Thesleeve 1021 may be pinned in place as indicated at 1024. Therear sleeve 1022 is mounted onbody 1020 onbearings 1025 for rotary motion thereon. The rear body portion is connected to a hydraulic or air line for supply of a pressurized operating fluid to the tool. - In the embodiments of Figs. 43 and 44, the protruding
anvil portion 1035 was not provided with any special boring surface. In the embodiments of Figs. 45 and 46, the tool has a slanted nose member which causes to tool to deviate from a straight boring path at an angle or along an arcuate path. The rear of the tool has controllable fins which allow the tool to move without rotation or to rotate about its longitudinal axis. This arrangement is described further below. - In Fig. 45, there is shown a
boring tool 1010 having abody 1020 enclosing the percussion mechanism driving the tool. The front end ofbody 1020 is tapered as at 1029 and has theexternal portion 1035 of the anvil protruding therefrom for percussion boring. The protrudingportion 1035 of the anvil has a slantednose member 1018 secured thereon for angular or arcuate boring. -
Front sleeve 1021 andrear sleeve 1022 are mounted on tool body orhousing 1020 by a shrink or interference fit. In this embodiment, theovergage sleeves - At the rear of
body 1020, there is arotatable housing 1019a on which there arefins 1017. The housing and fin assembly is actuatable between an inactive position in which the tool does not rotate about its axis and an actuated position where the fins cause the tool to rotate. The rear body portion is connected to a hydraulic or air line for supply of a pressurized operating fluid to the tool. - In Fig. 46, there is shown another embodiment of the boring tool in which one of the overgage sleeves is free to rotate. In this embodiment,
boring tool 1010 has abody 1020 enclosing the percussion mechanism driving the tool. The front end ofbody 1020 is tapered as at 1029 and has theexternal portion 1035 of the anvil protruding therefrom for percussion boring. The protrudingportion 1035 of the anvil has a slantednose member 1018 secured thereon for angular or arcuate boring:Front sleeve 1021 is mounted on tool body orhousing 1020 by a shrink or interference fit. Theovergage sleeve 1021 is fixed against longitudinal or rotational slippage. Thesleeve 1021 may be pinned in place as indicated at 1024. Therear sleeve 1022 is mounted on thebody 1020 onbearings 1025 for rotary motion thereon. - At the rear of
body 1020, there is arotatable housing 1019a on which there arefins 1017. The housing and fin assembly is actuatable between an inactive position in which the tool does not rotate about its axis and an actuated position where-the fins cause the tool to rotate. The rear body portion is connected to a hydraulic or air line for supply of a pressurized operating fluid to the tool. - Figs. 47A, 47B, and 47C illustrate a
boring tool 1027 having a slanted nose member and fixed/lockable fin arrangement as described generally in reference to Figs. 1 and 2 above. As shown,boring tool 1010 comprises an elongated hollow cylindrical outer housing orbody 1028. The outer front end ofbody 1028 tapers inwardly forming aconical portion 1029.Sleeve member 1021 is secured onbody member 1028 by a shrink or interference fit and is fixed against longitudinal or rotary slippage as previously described. The outside diameter ofbody 1028 tapers inwardly near the front end forming aconical surface 1030 which terminates in a reduceddiameter 1031 extending longitudinally inward from the front end. The rear end of thebody 1028 hasinternal threads 1032 for receiving a tail fin assembly (see Fig. 47C). - An
anvil 1033 having aconical back portion 1034 and an elongated cylindricalfront portion 1035 is positioned in the front end ofbody 1028. Theconical back portion 1034 ofanvil 1033 forms an interference fit on theconical surface 1030 of thebody 1028, and the elongatedcylindrical portion 1035 extends outwardly a predetermined distance beyond the front end of the body. A flattransverse surface 1036 at the back end of theanvil 1033 receives the impact of areciprocating hammer 1037. -
Reciprocating hammer 1037 is an elongated cylindrical member slidably received within thecylindrical recess 1038 of thebody 1028. A substantial portion of the outer diameter of thehammer 1037 is smaller in diameter than therecess 1038 of thebody 1028, forming anannular cavity 1039 therebetween. A relativelyshorter portion 1040 at the back end ofhammer 1037 is of larger diameter to provide a sliding fit against the interior wall ofrecess 1038 ofbody 1028. - A
central cavity 1041 extends longitudinally inward a distance from the back end of thehammer 1037. Acylindrical bushing 1042 is slidably disposed within thehammer cavity 1041, the circumference of which provides a sliding fit against the inner surface of thecentral cavity 1041. Thefront surface 1043 of the front end of thehammer 1037 is shaped to provide an impact centrally on theflat surface 1036 of theanvil 1033. As described above, the hammer configuration may also be adapted to deliver an eccentric impact force on the anvil. -
Air passages 1044 in the sidewall ofhammer 1037 inwardly adjacent the shorterrear portion 1040 communicate thecentral cavity 1041 with theannular cavity 1039. Anair distribution tube 1045 extends centrally through thebushing 1042 and has aback end 1046 extending outwardly of thebody 1028 connected byfittings 1047 to a flexible hose 1048. For reciprocating thehammer 1037, theair distribution tube 1045 is in permanent communication with a compressed air source 11 (Fig. 42). The arrangement of thepassages 1044 and thebushing 1042 is such that, during reciprocation of thehammer 1037, theair distribution tube 1045 alternately communicates via thepassages 1044, theannular cavity 1039 with either thecentral cavity 1041 or atmosphere at regular intervals. - A
cylindrical stop member 1049 is secured within therecess 1038 in thebody 1028 near the back end and has a series of longitudinally-extending, circumferentially-spacedpassageways 1050 for exhausting the interior of thebody 1028 to atmosphere and a central passage through which theair distribution tube 1045 extends. - A
slanted nose member 1018 has a cylindrically recessedportion 1052 with a centralcylindrical bore 1053 therein which is received on thecylindrical portion 1035 of the anvil 1033 (Fig. 47A). A slot 1054 through the sidewall of thecylindrical portion 1018 extends longitudinally substantially the length of thecentral bore 1053 and a transverse slot extends radially from thebore 1053 to the outer circumference of the cylindrical portion, providing flexibility to the cylindrical portion for clamping the nose member to the anvil. A flat is provided on one side ofcylindrical portion 1018 and longitudinally spaced holes are drilled therethrough in alignment with threaded bores on the other side.Screws 1059 are received in the holes and bores 1058 and tightened to securenose member 1018 toanvil 1033. - The sidewall of the
nose member 1018 extends forward from thecylindrical portion 1052 and one side is milled to form a flatinclined surface 1060 which tapers to a point at the extended end. The length and degree of inclination may vary depending upon the particular application. Thenose member 1018 may optionally have a flat rectangular fin 1061 (shown in dotted line) secured to the sidewall of thecylindrical portion 1052 to extend substantially the length thereof and radially outward therefrom in a radially opposed position to theinclined surface 1060. -
Slanted nose members 1018 of 2-1/2" and 3-1/2" diameter with angles from 10° to 40° (as indicated by angle "A") have been tested and show the nose member to be highly effective in turning the tool with a minimum turning radius of 28 feet being achieved with a 3-1/2inch 15° nose member. Testing also demonstrated that the turning effect of the nose member was highly repeatable with deviations among tests of any nose member seldom varying by more than a few inches in 35 feet of bore. Additionally, the slanted nose members were shown to have no adverse effect on penetration rate and in some cases, actuary increased it. - It has also been found that the turning radius varies linearly with the angle of inclination. For a given nose angle, the turning radius will decrease in direct proportion to an increase in area.
- The
rear sleeve 1022 is mounted on the rear portion ofhousing 1028 onbearings 1025 for rotary motion thereon. Thefront sleeve 1021 andrear sleeve 1022 provide a 2-point sliding contact on movement of the tool through the hole which is being bored. This provides for reduced friction and facilitates both the linear movement of the tool through the soil and on rotation of the tool by the fins. A tail fin assembly 1062 (19a in Fig. 42) is secured in the back end of the body 1028 (Fig. 47C). A fixed/lockabletail fin assembly 1062 is illustrated in the example and other variations will be described hereinafter. - The
tail fin assembly 1062 comprises a cyhn- drical connecting sub 1063 havingexternal threads 1064 at the front end which are received within theinternal threads 1032 at the back end of thebody 1028. Sub 1063 has a short reduced outsidediameter portion 1065 forming ashoulder 1066 therebetween and a second reduceddiameter 1067 adjacent theshort portion 1065 forms a second shoulder 1068. An 0-ring seal 1069 is located on the reduceddiameter 1065 intermediate theshoulders 1066 and 1068. Therear portion 1070 of the sub 1063 is smaller in diameter than the second reduceddiameter 1067 forming athird shoulder 1071 therebetween and provided with circumferential 0-ring seal 1072 and internal O-ring seal 1073.Internal threads 1074 are provided in therear portion 1070 inwardly of theseal 1073. Acircumferential bushing 1075 of suitable bearing material such as bronze is provided on the second reduced diameter. - A series of longitudinal circumferentially spaced grooves or
keyways 1076 are formed on the circumference of therear portion 1070 of the sub 1063. Ahollow cylindrical piston 1077 is slidably received on the circumference of therear portion 1070. A series of longitudinal circumferentially spaced grooves orkeyways 1078 are formed on the interior surface at the front portion of thepiston 1077 in opposed relation to thesub keyways 1076. A series of keys ordowel pins 1079 are received within thekeyways piston 1077. - A first
internal cavity 1080 extends inwardly from thekeyway 1078 terminating in a short reduceddiameter portion 1081 which forms ashoulder 1082 therebetween. Asecond cavity 1083 extends inwardly from theback end 1084 of thepiston 1077 terminating at the reduceddiameter portion 1081. An internal annular O-ring seal 1085 is provided on the reduceddiameter portion 1081. As shown in Fig. 47C, a series ofdrive teeth 1086 are formed on the back end of thepiston 1077. Theteeth 1086 comprise a series of circumferentially spaced raised surfaces 1087 having a straight side and an angularly sloping side forming a ratchet. Aspring 1090 is received within thefirst cavity 1080 of thepiston 1077 and is compressed between theback end 1070 of the sub 1063 and theshoulder 1082 of thepiston 1077 to urge the piston outwardly from the sub. - An elongated, hollow cylindrical
rotating fin sleeve 1091 is slidably and rotatably received on the outer periphery of the sub 1063. Thefin sleeve 1091 has a centrallongitudinal bore 1092 and a short counterbore 1093 of larger diameter extending inwardly from the front end and defining anannular shoulder 1094 therebetween. The counterbore 1093 fits over the short reduceddiameter 1065 of the sub 1063 with the 0-ring providing a rotary seal therebetween. A flatannular bushing 1095 of suitable bearing material such as bronze is disposed between theshoulders 1068 and 1094 to reduce friction therebetween. - A hollow
cylindrical sleeve 1097 is secured withinsleeve 1091 by suitable means such as welding. Thesleeve 1097 has acentral bore 1098 substantially the same diameter as thesecond cavity 1083 of thepiston 1077 and acounterbore 1099 extending inwardly from the back end defining ashoulder 1100 therebetween. As shown in Fig. 47C, a series ofdrive teeth 1101 are formed on the front end of thesleeve 1097. Theteeth 1101 comprise a series of circumferentially spaced raised surfaces 1102 having a straight side and an angularly sloping side forming a one-way ratchet configuration. The teeth correspond in opposed relationship to theteeth 1086 of thepiston 1077 for operative engagement therewith. - A series of flat radially and angularly opposed
fins 1105 are secured to the exterior of thefin sleeve 1091 to extend radially outward therefrom. - (Fig. 47C) Thefins 1105 are secured at opposing angles relative to the longitudinal axis of thesleeve 1091 to impart a rotational force on the sleeve. - An elongated
hollow cap sleeve 110 havingexternal threads 1107 at the front end is slidably received within the slidingpiston 1077 and thesleeve 1097 and threadedly secured in theinternal threads 1074 at therear portion 1070 of the sub 1063. Thecap sleeve 1106 extends rearwardly from thethreads 1107 and an enlarged diameter portion 1108 forms afirst shoulder 1109 spaced from the threaded portion and a secondenlarged diameter 110 forms asecond shoulder 1111 spaced from the first shoulder. An O-ring seal 1112 is provided on enlarged diameter 1108 nearshoulder 1109 and a second 0-ring seal 1113 is provided on the secondenlarged diameter 1110 near thesecond shoulder 1111. The O-ring 1112 forms a reciprocating seal on the interior of thesecond cavity 1083 of thepiston 1077 and the O-ring 113 forms a rotary seal on thecounterbore 1099 of thesleeve 1097. The 0-ring 1085 in thepiston 1077 forms a reciprocating seal on the extended sidewall of thecap 1106. - An annular chamber 1114 is formed between the exterior of the sidewall of the
cap 1106 and thesecond counterbore 1083 which is sealed at each end by the O-rings circumferential bushing 115 is provided on the first enlarged diameter 1108 and anannular bushing 116 on the secondenlarged diameter 110 is captured between theshoulders sleeve 1097 and thecap 1106. The rear portion of thecap 1106 hassmall bores 1117 arranged to receive a spanner wrench for effecting the threaded connection. A threadedbore 1118 at the back end ofcap 1106 receives a hose fitting - (not shown) andsmall passageway 1119 extends inwardly from the threadedbore 1118 to communicate annular chamber 1114 with a fluid or air source (not shown). A flexible hose extends outwardly of thecap 1106 and is connected to the fluid or air source for effecting reciprocation of thepiston 1077. A secondsmall passageway 1120 communicatesfirst cavity 1080 with atmosphere to relieve pressure which might otherwise become trapped therein.Passage 120 may also be used for application of pressure to the forward end ofpiston 1077 for return movement. - The tool described above is capable of horizontal guidance, has overgage body sections, and is preferably used with a magnetic field attitude sensing system. The boring tool may be used with various sensing systems, and a magnetic attitude sensing system is depicted generally as one example. The overgage sleeves may be fixed or rotatable on bearings as described above. Likewise, the overgage sleeves may be used with any percussion boring tool of this general type and is not limited to the particular guidance arrangement, i.e., the slanted nose member and controllable tail fins, described above. It is especially noted that any of the arrangements described in our copending patent application can be used with overgage sleeves to obtain the desired advantages.
- The procedure for using this percussion tool is to first locate and prepare the launching and retrieval pits. As described above, the launching pit P is dug slightly deeper than the planned boring depth and large enough to provide sufficient movement for the operator. The
boring tool 1010 is connected to a pneumatic orhydraulic source 11, is then started in the soil, stopped and properly aligned, preferably with a sighting frame and level. The tool is then restarted and boring continued until the tool exits into the retrieval pit (not shown). - The tool can move in a straight direction when used with an eccentric boring force, e.g., the slanted nose member or the eccentric hammer or anvil, provided that the fins are positioned to cause the tool the rotate about its longitudinal axis. When the fins are set to allow the tool to move without rotation about the longitudinal axis, the eccentric boring forces cause it to move either at an angle or along an arcuate path.
- As previously described, the overgage sleeves, which are located over a portion of the tool outer surface, are affixed such that they can rotate but cannot slide axially. This permits transmittal of the axial impact force from the tool to the soil while allowing free rotation of the tool during spinning operations. The overgage areas are at the front and back of the tool, or alternately, an undergage section in the center of the tool body. This undercut in the center of the tool permits a 2-point contact - (front and rear) of the tool's outer housing with the soil wall as opposed to the line contact which occurs without the undercut. The 2-point contact allows the tool to deviate in an arc without distorting the round cross-sectional profile of the pierced hole. Thus, for a given steering force at the front and/or back of the tool, a higher rate of turning is possible since a smaller volume of soil needs to be displaced.
- In the embodiment shown, for turning the tool, the
tail fins 1017 are moved into a position where they may spin about the longitudinal axis of thetool 1010 and theslanted nose member 1018 or eccentric hammer will deflect the tool in a given direction. When thefins 1017 are moved to a position causing thetool 1010 to rotate about its longitudinal axis, the rotation will negate the turning effect of thenose member 1018 or eccentric hammer as well as provide the means for orienting the nose piece into any given plane for subsequent turning or direction change. - The front 1021 and rear 1022 overgage body sections give improved performance of the tool both in straight boring and in angular or arcuate boring. These overgage sections are fixed longitudinally on the tool body and may be fixed against rotation or may be mounted on bearings which permit them to rotate.
- While the overgage sleeves can be used with any percussion boring tool, they have been shown in combination with one the embodiments described above. The operation of this percussion
boring tool 1027 is as follows. Under action of compressed air or hydraulic fluid in thecentral cavity 1041, thehammer 1037 moves toward the front of thebody 1028. At the foremost position, the hammer imparts an impact on theflat surface 1036 of theanvil 1033. - In this position, compressed air is admitted through the
passages 1044 fromcentral cavity 1041 into theannular cavity 1039. Since the effective area of the hammer includding the larger diameterrear portion 1040 is greater than the effective area of thecentral cavity 1041, the hammer starts moving in the opposite direction. During this movement, thebushing 1042 closes thepassages 1044, thereby interrupting the admission of compressed air intoannular cavity 1041. - The
hammer 1037 continues its movement by the expansion of the air in theannular cavity 1039 until thepassages 1044 are displaced beyond the ends of thebushing 1042, and the annular cavity exhausts to atmosphere through theholes 1050 in thestop member 1049. Then the cycle is repeated. - The operation of the
tail fin assembly 1062 is best seen with reference to Fig. 47C. The compressed air or fluid in the annular cavity 1114 moves thepiston 1077 against thespring 1090 and toward the front of the sub 1063. In the foremost position, the front end of thepiston 1077 contacts theshoulder 1071 and thedrive teeth 1086 and 10101 become disengaged. In this position, compressed air or fluid is admitted through thepassage 1119 from the source into the annular chamber 1114. Thefin sleeve 1091 is then free to rotate relative to the tool body. Pressure which may otherwise become trapped in thefirst cavity 1080 and hinder reciprocation is exhausted through thepressure relief passage 1120 to atmosphere. - When the air or fluid pressure within the chamber 1114 is relieved, the force of the
spring 1090 moves thepiston 1077 in the opposite direction. During this movement, thedrive teeth fin sleeve 1091 becomes locked against rotational movement relative to the tool body. The cycle may be selectively repeated as necessary for proper alignment the slantednose member 1018 and attitude adjustment of the tool. It should be understood that thepassage 1120 may also be connected to a fluid source, i.e. liquid or air, for moving the piston to the rearward position. - The reciprocal action of the hammer on the anvil and nose member as previosuly described produces an eccentric or asymmetric boring force which causes the tool to move forward through the earth along a path whcih deviates at an angle or along an arcuate path when the tool is not rotating. When the tool is rotated by operation of the fins, it moves along a substantially straight path (actually a very tight spiral). The overgage sleeves support the tool housing at two separ ated points. This 2- point contact (front and rear) of the tool housing with the soil wall allows the tool to deviate in an arc without distorting the round cross-sectional profile of the pierced hole. Thus, for a given steering force at the front and/or back of the tool, a higher rate of turning is possible since a smaller volume of soil needs to be displaced and the helix length is reduced.
- This embodiment relates to the control of the guidance of a percussion boring tool, especially using a magnetic sensing system or sensing tool location and attitude.
- In the installation of conduits and pipes by various utilities, such as gas, telephone and electric utilities, a problem often faced is the need to install or replace such conduits or pipes under driveways, roads, streets, ditches and/or other structures. To avoid unnecessary excavation and repair of structures, the utilities use horizontal boring tools to form the bore holes in which to install the conduits or pipes. Such tools have been unsatisfactory to the extent that their traverse has not been accurate or controllable. All to frequently other underground utilities have been pierced or the objective target has been missed by a substantial margin. It has aso been difficult to steer around obstacles and get back on course.
- In Fig. 48 is illustrated horizontal boring operation in which a
borehole 1210 is being bored through the earth 1212 under aroadway 1214 by a horizontalboring tool 1216. The particular tool illustrated and for which the preferred embodiment of the present invention was specifically designed is a pneumatic percussion tool, operated like a jack- hammer by amotive mechanism 1217 using compressed air supplied by acompressor 1218 by way of anair tank 1219 over asupply hose 1220. Thetool 1216 is elongated and has atool axis 1222 extending in the direction of its length. The lead end of thetool 1216 has a piercing point (or edge) 1224 eccentric of he axis 1222. The operation of the percussion tool drives thepoint 1224 through the earth, advancing the tool forward, but slightly off axis. - The
tool 1216 includes a plurality ofsteering vanes 1226 which may be actuated by pneumatic or hydraulic control energy provided over pneumatic orhydraulic control lines 1228 from acontroller 1230 to control the direction and rate rotation of hetool 1216 about its axis. Control signals may also control the operation of themotive mechanism 1217. Thecontroller 1230 is supplied with air from thecompressor 1218 over abore 1232. - The
steering vanes 1226 my be turned to cause the tool to rotate at a relatively constant rate. - The tool then spirals a bit but advances in a substantially straight line in the direction of the
axis 1222 because thepiercing point 1224 circles the axis and causes the tool to deviate the same amount in each direction, averaging zero. If thevanes 1226 are returned to directions parallel to theaxis 1222, the rotation may be stopped with the tool in a desired position, from which it advances asymmetrically in a desired direction. - As will be described below, the present invention permits an operator to identify the rotational orientation of the
tool 1216 about itsaxis 1222, and hence, to direct the advance of the tool. The objective is to bore ahole 1210 relatively horizontally between aninput pit 1234 and atarget pit 1236 beneath such obstacles as theroadway 1214. Thehole 1210 must avoid piercingother utility lines 1238 orsewers 1240 or other buried obstacles. These may be identified and located from historical surveyor's drawings or may be located by some other means as by a metal detector or other proximity device 1242. - Armed with this information, an operator may start the tool off easily enough from the
input pit 1236 in a direction that avoids nearby obstacles and may plot a course that would miss all more distant obstacles. Thedifficulty is in assuring that the tool follows the plotted course. That is the function of the present invention. The present invention is directed to a control system for sensing the attitude of thetool 1216 and for controlling thesteering vanes 1226 to direct the tool along the plotted course. The control system includes anelectromagnetic source 1244 affixed to thetool 1216 for generating appropriate alternating magnetic flux, asensing assembly 1246 disposed in one of thepits target pit 1236, and circuitry in thecontroller 1230 which is powered from a motor-generator set 1248. - Reference may be made to Fig. 49 for an understanding of the preferred arrangement of the
electromagentic source 1244 and thesensing assembly 1246. Theelectromagnetic source 1244 comprises anaxial coil 1250 and atransverse coil 1251 rigidly mounted on thetool 1216. Thecoils generator power source 1248 through a controlledpower supply section 1252 of thecontroller 1230 overlines 1253. Thepower source 1248 operates at a relatively low frequency, for example, 1220 Hz. - The
axial coil 1250 generates an axial alternating magnetic field which produces lines of magnetic flux generally symmetrically about theaxis 1222 of thetool 1216, as illustrated in Fig. 50. Thetool 1216 itself is constructed in such manner as to be compatible with the generation of such magnetic field and, indeed , to shape it appropriately. Thetransverse coil 1251 generates a transaxial alternating magnetic field substantially orthogonal to theaxis 1222 in fixed relation to the direction of deviation of thepoint 1224 from theaxis 1222 and, hence, indicative of the direction thereof. - The
sensing assembly 1246 is formed of threeorthogonal pickup coils coils - In Figs. 50A, 50B, 50C and 50D are illustrated four possible unique relationships of a sensing coil, the
Y coil 1256 as an example, to the lines offlux 60 of the axial magnetic field generated by theaxial coil 1250 in thetool 1216. In Fig. 50A is shown the relationship when the X axis and thetool axis 1222 lie in the same plane with the Y axis of hecoil 1256 normal to that plane. That is the relationship when thetool 1216 lies on the plane XZ (the plane perpendicular to the Y axis at the X axis) with theaxis 1222 of the tool in that plane. In Fig. 50B is shown the relationship when thetool 1216 lies in the plane XZ with thetool axis 1222 not in that plane. That is the relationship when thetool 1216 is tilted up or down (up, clockwise, in the example illustrated). In Fig. 50C is shown the relationship when thetool 1216 is displaced up or down from the plane XZ (up, in the example illustrated) with thetool axis 1222 parallel to the plane XZ. Other relationships involve combinations of the relationships shown in Figs. 50B and 50C; that is, where thetool 1216 ties off the XZ plane and has a component of motion transversely thereof. Shown in Fig. 50D is the relationship where the combination of displacement (Fig.50C) and tilting (Fig. 50B) places the coil axis Y normal to the Ines offlux 1260 at the coil. The lines of flux shown in Figs. 50A, 50B, 50C and 50D are for conditions whentool axis 1222 lines in the XY plane - (containing the X and Y axes), but the principle is the same when the tool lies out of such plane. The lines of flux linkingY coil 1256 would be different, and the relative signals would be somewhat different. There would, however, still be positions of null similar to those illustrated by Figs. 50A and 50D. - As can be seen by inspection and from the principle of symmetry, the
pickup coil 1256 will generate no signal under the condition shown in Fig. 50A because no flux links the coil. On the other hand, under the conditions of Figs. 50B and 50C, signals will be generated, of phase dependent upon which direction the magnetic field is tilted or displaced from the condition shown in Ftg. 50A. Further, under the condition shown in Fig. 50D, the effect of displacement in one direction is exactly offset by tilting so as to generate no signal. As may also be seen from Fig. 50D, if thetool 1216 is off course (off the XZ plane) but the relationship shown in Fig. 50D is maintained, the tool will move toward thesensing assembly 1246 keeping the sensing assembly on a given line offlux 1260. That is, thetool 1216 will home in on thesensing assembly 1246 and get back on course vertically. Similar relationships exist in respect to theZ coil 1258 and horizontal deviation. The outputs of the pickup coils 1256, 1258 are applied through asignal conditioner 1262 to adisplay 1264 in thecontroller 1230. - The relatinships shown in Fig. 50 can also be analyzed geometrically as shown in Fig. 50, where A is the angle between the
tool axis 1222 and aline 1265 connecting the center of the tool with the center of thepickup coil 1256, and B is the angle between theline 1265 and the reference axis X, perpendicular to the axis Y of thesensing coil 1256. - The well know equation for radial flux density BRand angular flux density BA are:
axial coil 1250 and inversely proportional to the cube of th distance between thetool 1216 and thesensing coil 1256. The singal V thereupon developed in thepickup coil 1256 is proportional to the sum of flux components parallel to the coil axis Y. - That is,
coil 1256 is normal to its axis Y, the two components balance, i.e., BR sin B = -BA cos B, making V = 0. - The circuitry for operating the present invention is shown in greater detail in Fig. 51 in block diagram form. As there shown, the output of the
pickup coil 1256 is amplified by anamplifier 1266 and applied to asynchronous detector 1268 to which the output of aregulated power supply 1270 is also applied. Theregulated power supply 1270 is driven by the same controlledpower supply 1252 that drives thecoils axial coil 1250. - The
synchronous detector 1268 therefore produces a d.c. output of magnitude proportional to the output of theY coil 1256 and of polarity indicative of phase relative to that of thepower supply 1270. Anamplifier 1272 and asynchronous detector 1274 produce a similar d.c. output corresponding to the output of theZ coil 1258. The outputs of the respectivesynchronous detectors display 1264 which displays in y, z coordi-nates the combination of the two signals. This indicates the direction or attitude the tool is off course, permitting the operator to provide control signals over thecontrol lines 1228 to return the tool to its proper course or to modify the course to avoid obstacles, as the case may be. - The extent to which the tool is off a course leading to the target is indicated by the magnitude of the signals produced in the
coils respective pickup coils X coil 1254 to remove this variable. The X coil is sensitive to axial flux density substantially exclusively. The y and z directed flux components have negligible effect on its output where thetool 1216 lies within a few degrees of the x direction; e.g., 123. - The signal from the
pickup coil 1254 is amplified by anamplifier 1276 and detected by asynchronous detector 1278 to provide a d. c. output proportional to the flux density strength at theX coil 1254. This signal is applied to acontrol circuit 1280 which provides a field current control for thepower supply 1252. This provides feedback to change the power applied to theaxial coil 1250 in such direction as to maintain constant the output of theX coil 1254. - This makes the flux density at the
sensing assembly 1246 relatively constant, thus normalizing the outputs of the Y and Z coils 1256, 1258 and making these outputs relatively independent of range. However, if wide deviations from dir ect paths between the launch and exit points are expected, the total magnitude of the magnetic flux density should be used for this normalizing function. This magnitude may be developed by appropriately combining the outputs from the three pickup coils. - It is one thing to know where the tool is and its attitude. It is another to return it to its course. That is the function of the
transverse coil 1251. The power from thepower supply 1252 is applied to thetool 1216 through a switch 1282. - When in the switch 1282 position 121, the
axial coil 1250 is energized, providing the mode of operation explained above. With the switch 1282 in position 122, thetransverse coil 1251 is energized instead. The resulting magnetic field is substantially orthogonal to that provided by theaxial coil 1250. The signals generated by the Y andZ pickup coils coil 1251 around theaxis 1222. - Because the
coil 1251 is mounted in fixed relationship to thepiercing point 1224, the displacement of the point is indicated by the relative magnitude of the respective signals from the respective Y and Z coils as detected by the respectivesynchronous detectors display 1264. - This enables the operator to position the
tool 1216 about its axis by controllinbg the position of thevanes 26 and thereby cause thetool 1216 to advance in desired direction relative to isaxis 1222. The feedback by way of thecontroller circuit 1280 is not used in this mode, as the signal from theX coil 1254 is near zero in this mode. - The present invention is useful in a simple form when it is desirable simply to keep the tool on a straight course. This is achieved simply by directing the
tool 1216 toward thesensing assembly 1246 while keeping the outputs picked up by the Y and Z coils 1256, 1258 nulled. As mentioned above, it is possible to deviate to avoid obstacles and then return to the course. - This is facilitated by keeping track of where the tool is at all times. This requires measurement of the tool advance within the borehole. Although this is indicated to a degree by the power required to maintain constant the output of the
X coil 1254, it is more accurate to measure x displacement along the borehole more directly by measuring the length oflines 1253 fed into the borehole or by a distance indicating potentionmeter 1284 tied to thetool 1216 by aline 1286. This provides a signal on aline 1288 indicating displacement and incremental displacement of thetool 1216 within the borehole. This information, in combination with the signals from Y and Z coils 1256, 1258 permits the operator to keep track of the location of the tool at all times. - When distance is kept track of and position is determined, it is possible by more sophisticated electronics to operate with the sensing assembly in the
input pit 1234, particularly if thetool 1216 kept substantially on the x axis. For example, if the tool is allowed to progress a substantial distance from the desired axis, the angle B becomes significant and a more complicated set of relationships apply than when the size of the angle B is near 0 and its cosine 121. That is, Equation (4) may not be simply approximated. - In this case, it will be necessary to continuously develop the position of the tool in order to provide accurate data on its location. In this case, the initial tool orientation is determined by means of the sensor coils. Then the tool is allowed to advance an incremental distance, which is also measured. The new location is then determined based on the initial angle and the incremental amount of progress, and integration process. This process is continuously repeated for continuous determination of the position of the tool.
- Other modifications of the present invention are also possible. For example, the
sensing assembly 1246 may be moved from place to place or its orientation charged during boring in order to change course. Also the sensor coils can be located on the tool and the source coils can be located on the tool and the source coils placed in either pit It is also within the scope of the present invention to provide sensors on thetool 1216 for sensing obstacles, hence permit ting control of the direction of tool advance to avoid the obstacles-Other types of boring or drilling systems can be used in conjunction with the present invention, such as hydraulic percussion tools, turbo-drill motors (pneumatic or hydraulic) or rotary-drift type tools. The important aspects of the tool are that it include some motive means and a steering mechanism that can be controlled by control signals from afar.
Claims (76)
said anvil boring surface comprises a cylindrical nose portion having a side face extending longitudinally from the tip at an acute angle thereto.
said external anvil boring surface comprises a cylindrical body and said nose portion is removably secured thereon.
said hammer member has an asymmetric end portion for applying said asymmetric earth boring force.
said hammer member has a cylindrical body portion and an end portion asymmetric to the anvil end of said anvil member for applying a hammer blow adjacent to the periphery thereof for applying said asymmetric earth boring force.
said external anvil boring surface comprises a cylindrical body and said nose portion is removably secured thereon.
said hammer member has an asymmetric end portion for applying said asymmetric earth boring force.
said hammer member has a cylindrical body portion and an end portion asymmetric to the anvil end of said anvil member for applying a hammer blow adjacent to the periphery thereof for applying said asymmetric earth boring force.
said source of actuating fluid comprises a source of hydraulic fluid under pressure.
said third part comprises a sleeve member slidably movable of said supporting sleeve portion and within said rotatable sleeve member and having drive surfaces operatively engagable with said rotatable sleeve member and said supporting sleeve portion to secure the same for movement together.
said slidable sleeve member is movable between a position engaged with and a position disengaged from said rotatable sleeve member and said supporting sleeve portion.
said drive teeth are positioned for end to end engagement
said drive member comprises a drive pin.
said drive member ccomprises a drive pin.
said source of actuating fluid comprises a source of compressed air for pneumatic operation.
said source of actuating fluid comprises a source of hydraulic fluid under pressure.
said percussion operated tip comprises a cylindrical nose portion having a side face extending longitudinally from the tip at an acute angle thereto.
said percussion operated tip comprises a cylindrical body and said nose portion is removably secured thereon.
said hammer member has a asymmetric end portion for applying said asymmetric earth boring force.
said hammer member has a cylindrical body portion and an end portion asymmetric to the anvil end of said anvil member for applying a hammer blow adjacent to the periphery thereof for applying said asymmetric earth boring force.
said sleeve members are secured on said housing aginst longitudinal movement thereon.
at least one of said sleeve members is secured on said housing for rotary movement thereon.
said housing includes a friction bearing member on the outer surface thereof in bearing relation with said at least one sleeve member to permit rotary movement thereof.
said sleeve members are secured on said housing against longitudinal movement thereon.
at least one of said sleeve members is secured on said housing for rotary movement thereon.
said housing includes a friction bearing member on the outer surface thereof in bearing relation with said at least one sleeve member to permit rotary movement thereof.
at least one of said sleeve members is secured on said housing for rotary movement thereon.
said housing includes a friction bearing member on the outer surface thereof in bearing relation with said at least one sleeve member to permit rotary movement thereof.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT86302534T ATE86355T1 (en) | 1985-04-05 | 1986-04-04 | GUIDANCE AND CONTROL SYSTEM FOR IMPACT DRILLING TOOLS. |
EP90122531A EP0428181B1 (en) | 1985-04-05 | 1986-04-04 | Percussion tool for drilling holes in the soil |
EP90122530A EP0428180B1 (en) | 1985-04-05 | 1986-04-04 | Control system for guiding boring tools and a sensing system for locating the same |
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US720582 | 1985-04-05 | ||
US06/720,582 US4632191A (en) | 1985-04-05 | 1985-04-05 | Steering system for percussion boring tools |
US722807 | 1985-04-12 | ||
US06/722,807 US4646277A (en) | 1985-04-12 | 1985-04-12 | Control for guiding a boring tool |
US723792 | 1985-04-16 | ||
US06/723,792 US4621698A (en) | 1985-04-16 | 1985-04-16 | Percussion boring tool |
Related Child Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP90122530.0 Division-Into | 1990-11-26 | ||
EP90122531.8 Division-Into | 1990-11-26 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0202013A2 true EP0202013A2 (en) | 1986-11-20 |
EP0202013A3 EP0202013A3 (en) | 1988-08-03 |
EP0202013B1 EP0202013B1 (en) | 1993-03-03 |
Family
ID=27419012
Family Applications (3)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP90122530A Expired - Lifetime EP0428180B1 (en) | 1985-04-05 | 1986-04-04 | Control system for guiding boring tools and a sensing system for locating the same |
EP90122531A Expired - Lifetime EP0428181B1 (en) | 1985-04-05 | 1986-04-04 | Percussion tool for drilling holes in the soil |
EP86302534A Expired - Lifetime EP0202013B1 (en) | 1985-04-05 | 1986-04-04 | Steering and control system for percussion boring tools |
Family Applications Before (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP90122530A Expired - Lifetime EP0428180B1 (en) | 1985-04-05 | 1986-04-04 | Control system for guiding boring tools and a sensing system for locating the same |
EP90122531A Expired - Lifetime EP0428181B1 (en) | 1985-04-05 | 1986-04-04 | Percussion tool for drilling holes in the soil |
Country Status (5)
Country | Link |
---|---|
EP (3) | EP0428180B1 (en) |
AT (3) | ATE86355T1 (en) |
AU (1) | AU589615B2 (en) |
CA (2) | CA1255651A (en) |
DE (3) | DE3687855T2 (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
BE1001218A3 (en) * | 1987-11-12 | 1989-08-22 | Smet Marc Jozef Maria | Detection device for boring head - has earth removing parts at end of flexible boring casing and series of direction sensitive detector and electromagnetic coil |
WO1989007690A1 (en) * | 1988-02-10 | 1989-08-24 | Ronald Albert William Clarke | Apparatus for reflex-percussive cutting of concrete etc. |
GB2382143A (en) * | 2000-05-01 | 2003-05-21 | Schlumberger Holdings | A method for telemetering data between wellbores |
US6705415B1 (en) | 1999-02-12 | 2004-03-16 | Halco Drilling International Limited | Directional drilling apparatus |
CN109372424A (en) * | 2018-12-13 | 2019-02-22 | 长江大学 | A kind of coiled tubing composite impact speed-raising drilling tool |
CN112443274A (en) * | 2019-08-27 | 2021-03-05 | 永城煤电控股集团有限公司 | Construction method of coal bunker cable hole |
CN113756788A (en) * | 2021-10-18 | 2021-12-07 | 中国地质大学(北京) | Mechanical type is along with boring well deviation measuring apparatu |
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US4878547A (en) * | 1988-10-28 | 1989-11-07 | Ingersoll-Rand Company | Rock drilling apparatus |
JP2819042B2 (en) * | 1990-03-08 | 1998-10-30 | 株式会社小松製作所 | Underground excavator position detector |
DE4438934C1 (en) * | 1994-10-31 | 1995-11-16 | Tracto Technik | Location device for ram boring appts. |
WO1996018118A1 (en) * | 1994-12-08 | 1996-06-13 | Noranda Inc. | Method for real time location of deep boreholes while drilling |
US6411094B1 (en) | 1997-12-30 | 2002-06-25 | The Charles Machine Works, Inc. | System and method for determining orientation to an underground object |
GB2341754B (en) * | 1998-09-19 | 2002-07-03 | Cryoton | Drill string telemetry |
DE19859367C2 (en) * | 1998-12-22 | 2003-03-20 | Tracto Technik | Steering head ram boring machine |
AU2001273549A1 (en) * | 2000-07-18 | 2002-01-30 | Geoff D. Koch | Remote control for a drilling machine |
US6871712B2 (en) | 2001-07-18 | 2005-03-29 | The Charles Machine Works, Inc. | Remote control for a drilling machine |
US6607045B2 (en) | 2001-10-10 | 2003-08-19 | Donald Beyerl | Steering apparatus |
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US11674354B2 (en) | 2020-11-03 | 2023-06-13 | The Charles Machine Works, Inc. | Piercing tool aiming device |
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- 1986-04-04 AT AT86302534T patent/ATE86355T1/en not_active IP Right Cessation
- 1986-04-04 EP EP90122530A patent/EP0428180B1/en not_active Expired - Lifetime
- 1986-04-04 DE DE8686302534T patent/DE3687855T2/en not_active Expired - Fee Related
- 1986-04-04 CA CA000505910A patent/CA1255651A/en not_active Expired
- 1986-04-04 EP EP90122531A patent/EP0428181B1/en not_active Expired - Lifetime
- 1986-04-04 DE DE3650461T patent/DE3650461T2/en not_active Expired - Fee Related
- 1986-04-04 EP EP86302534A patent/EP0202013B1/en not_active Expired - Lifetime
- 1986-04-04 DE DE3650026T patent/DE3650026T2/en not_active Expired - Fee Related
- 1986-04-04 AT AT90122530T patent/ATE132226T1/en not_active IP Right Cessation
- 1986-04-04 AT AT90122531T patent/ATE109866T1/en not_active IP Right Cessation
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Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
BE1001218A3 (en) * | 1987-11-12 | 1989-08-22 | Smet Marc Jozef Maria | Detection device for boring head - has earth removing parts at end of flexible boring casing and series of direction sensitive detector and electromagnetic coil |
WO1989007690A1 (en) * | 1988-02-10 | 1989-08-24 | Ronald Albert William Clarke | Apparatus for reflex-percussive cutting of concrete etc. |
US5066070A (en) * | 1988-02-10 | 1991-11-19 | Clarke Ronald A W | Apparatus for reflex-percussive cutting of concrete etc. |
US6705415B1 (en) | 1999-02-12 | 2004-03-16 | Halco Drilling International Limited | Directional drilling apparatus |
GB2382143A (en) * | 2000-05-01 | 2003-05-21 | Schlumberger Holdings | A method for telemetering data between wellbores |
GB2382143B (en) * | 2000-05-01 | 2004-05-26 | Schlumberger Holdings | A method for telemetering data between wellbores |
CN109372424A (en) * | 2018-12-13 | 2019-02-22 | 长江大学 | A kind of coiled tubing composite impact speed-raising drilling tool |
CN109372424B (en) * | 2018-12-13 | 2023-09-29 | 长江大学 | Composite impact speed-increasing drilling tool for coiled tubing |
CN112443274A (en) * | 2019-08-27 | 2021-03-05 | 永城煤电控股集团有限公司 | Construction method of coal bunker cable hole |
CN113756788A (en) * | 2021-10-18 | 2021-12-07 | 中国地质大学(北京) | Mechanical type is along with boring well deviation measuring apparatu |
Also Published As
Publication number | Publication date |
---|---|
EP0202013A3 (en) | 1988-08-03 |
DE3650461T2 (en) | 1996-05-15 |
CA1255651A (en) | 1989-06-13 |
DE3650026D1 (en) | 1994-09-15 |
ATE132226T1 (en) | 1996-01-15 |
EP0428180A1 (en) | 1991-05-22 |
CA1274817A (en) | 1990-10-02 |
EP0202013B1 (en) | 1993-03-03 |
EP0428180B1 (en) | 1995-12-27 |
EP0428181A1 (en) | 1991-05-22 |
DE3650461D1 (en) | 1996-02-08 |
DE3687855D1 (en) | 1993-04-08 |
DE3687855T2 (en) | 1993-07-01 |
ATE109866T1 (en) | 1994-08-15 |
ATE86355T1 (en) | 1993-03-15 |
AU5565286A (en) | 1986-10-09 |
AU589615B2 (en) | 1989-10-19 |
EP0428181B1 (en) | 1994-08-10 |
DE3650026T2 (en) | 1994-12-01 |
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